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The American Family In the American family the husband and wife usually share important dec...
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—I’mafraidnotforI_______ChinesetoAmericanstudentst
will teach
was teaching
will be teaching
taught
In1807NoahWebsterbeganhisgreatestworkAnAmericanDic
One volume.
Two volumes
Three volumes.
Four volumes.
In1807NoahWebsterbeganhisgreatestworkAnAmericanDic
respond to the need for new schoolbooks
show the distinct development of the English language in America
improve spelling forms based upon British models
influence the pronunciation of the English language
Isawaninterestingfilm.Thefilmwasadaptedfromafamou
EdisonwasoneofgreatAmericani
I'mnotbutIlikemusicverymuch.A.America;America B.\A
Differentsoundsmakethewholeworldmorelovelyespecial
I’mnot_______butIlike______musicverymuch.A.America
DWhenIsawabighandmadesignboardWelcomeYuxinattheair
WhenIwasyoungIenjoyedwatchingTomandJerryapopularAm
WhenIsawabighandmadesignboardWelcomeYuxinattheairp
I'mnotfrombutIlikemusicverymuch.A.America;America
In1807NoahWebsterbeganhisgreatestworkAnAmericanDic
1817.
1807.
1828.
1824.
I'mnotbutIlikesongsverymuch.A.American;American B.
阅读以下5段语言材料然后从A.B.C.D.和E.中选出符合他们要求的最佳选项66.ManyAmeri
----YouhaveneverseenanAmericanfilmhaveyou?----____
Yes, I have
Yes, I haven’t
No, I have
No, I haven’t
ItwasnotuntilIwasinjuredinacaraccident________ther
that I found out
when I found out
did I find out
that did I find out
America/I'm/American/but/I/don'tlivein .
IamnotbutIlikemusicverymuch.A.America;America B.Am
DoyoupreferBritishEnglishorAmericanEnglish?Hereare
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ByfarthemostcommonsnakeinBritainistheadder.InScotlandinfacttherearenoothersnakesatall.TheadderisalsotheonlyBritainsnakewithapoisonousbite.Itcanbefoundalmostanywherebutpreferssunnyhillsidesandroughopencountryincludinghighground.InIrelandtherearenosnakesatall. Mostpeopleregardsnakebitesasafatalmisfortunebutnotallbitesareseriousandveryfewarefatal:Sometimesattemptsatemergencytreatmentturnouttobemoredangerousthanthebiteitselfwithamateursheroicallybutmistakenlytryingdo-it-yourselfsurgeryandotherunnecessarymeasures. Allsnakeshavesmallteethsoitfollowsthatallsnakescanbitebutonlythebiteoftheadderpresentsanydanger.Britishsnakesareshyanimalsandarefarmorefrightenedofyouthanyoucouldpossiblybeofthem.Theadderwillattackonlyifitfeelsthreatenedascanhappenifyoutakeitbysurpriseandsteponitaccidentallyorifyoutrytocatchitorpickitupwhichitdislikeintensely.Ifithearsyoucomingitwillnormallygetoutofthewayasquicklyasitcanbutadderscannotmoveveryrapidlyandmayattackbeforemovingifyouareveryclose.Theeffectofabitevariesconsiderably.Itdependsuponseveralthingsoneofwhichisthebody-weightofthepersonbitten.Thebiggerthepersonthelessharmfulthebiteislikelytobewhichiswhychildrensufferfarmoreseriouslyfromsnakebitesthanadults.Ahealthypersonwillalsohavebetterresistanceagainstthepoison.VeryfewpeopleactuallydiefromsnakebitesinBritainandthoughthesebitescanmakesomepeopleveryillthereareprobablyjustasmanycasesofbiteshavinglittleornoeffectasthereareofseriousillness. Ifyouarewithsomeonewhoisbittenbyanadderyoushould.
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 61
WhatdoyoumeanbythatPaulaskedsharply
PuttingPlantstoWorkUsingthepowerofthesunisnothingnew.Peoplehavehadsolar-poweredcalculatorsandbuildingswithsolarpanelsfordecades.Butplantsaretherealexperts:They’vebeenusingsunlightasanenergysourceforbillionsofyears.Ceilsinthegreenleavesofplantsworkliketinyfactoriestoconvertsunlightcarbondioxideandwaterintosugarsandstarchesstoredenergythattheplantscanuse.Thisconversionprocessiscalledphotosynthesis.Unfortunatelyunlessyou’reaplantit’sdifficultandexpensivetoconvertsunlightintostorableenergy.That’swhyscientistsaretakingacloserlookatexactlyhowplantsdoit.Somescientistsaretryingtogetplantsorbiologicalcellsthatactlikeplantstoworkasminiaturephotosyntheticpowerstations.ForexampleMafiaGhirardioftheNationalRenewableEnergyLaboratoryinGoldenColo.isworkingwithgreenalgae.She’stryingtotrickthemintoproducinghydrogeninsteadofsugarswhentheyperformphotosynthesis.Oncetheresearcherscangetthealgaeworkingefficientlythehydrogenthattheyproducecouldbeusedtopowerfuelcellsincarsortogenerateelectricity.Thealgaearegrowninnarrow-neckedglassbottlestoproducehydrogeninthelabduringphotosynthesisplantsnormallymakesugarsorstarches.Butundercertainconditionsalotofalgaeareabletousethesunlightenergynottostorestarchbuttomakehydrogen.Ghirardisays.Forexamplealgaewillproducehydrogeninanairfreeenvironment.It’stheoxygenintheairthatpreventsalgaefrommakinghydrogenmostofthetime.Workinginanairfreeenvironmenthoweverisdifficult.It’snotapracticalwaytoproducecheapenergy.ButGhirardiandhercolleagueshavediscoveredthatbyremovingachemicalcalledsulfatefromtheenvironmentthatthealgaegrowintheywillmakehydrogeninsteadofsugarsevenwhenairispresent.Unfortunatelyremovingthesulfatealsomakesthealgae’scellsworkveryslowlyandnotmuchhydrogenisproduced.Stilltheresearchersseethisasafirststepintheirgoaltoproducehydrogenefficientlyfromalgae.Withmoreworktheymaybeabletospeedthecells’activityandproducelargerquantitiesofhydrogen.Theresearchershopethatalgaewillonedaybeaneasy-to-usefuelsource.TheorganismsarecheaptogetandtofeedGhirardisaysandtheycangrowalmostanywhere:YoucangrowtheminareactorinapondYoucangrowthemintheocean.There’salotofflexibilityinhowyoucanusetheseorganisms./Whatdoesthewritersayaboutplantsconcerningsolarenergy
{{*HTML*}}MemoryTest??1.IamgoingtogiveyoufivetechniquesthatwillenableyoutorememberanythingyouneedtoknowatschoolpromisedlecturerlanRobinsontoahundredschoolchildren.Heslappedhishanddownonthetable.WhenI’vefinishedintwohours’timeyourworkwillbefarmoreeffectiveandproductive.Anyonenotinterestedleavenow.Theentireroomsatstill.??2.RobinsoncallshimselftheMindMagician魔术师.Hespecializesindoingmagictricksthatlooktotallyimpossibleandthenherevealsthattheyinvolvenothingmoremysteriousthangoodold-fashionedtrickery骗术.Ihavealwaysbeeninterestedintricksinvolvingmemory-beingabletoreeloff一口气说出theorderofcardsinapackthatsortofthingheexplains.??3.Robinsonwasalreadylecturingtoschoolsonhismagictechniqueswhenitstruckhimthatstudentsmightfindmemorytechniquesevenmorevaluable.Itwasn’tdifficultareatomoveinotasthestuff’sallthereinbooks.Sohesummarizedeverythingtomakeatwo-hourlectureaboutfivetechniques.??4.Youwanttolearnalistofahundredthings?Athousand?NoproblemsaysRobinson.Thescandalisthateverychildisnottaughtthetechniquesfromthebeginningoftheirschoollife.Theschoolchildrenwhowerewatchinghimthoughtitwasbrilliant.IwishI’dbeentoldthisearliercommentedMarkafterRobinsonhadshownthemhowtoconstructmentaljourneys.??5.Essentiallyyouvisualize想象awalkdownastreetoratriproundaroomandpickthepointswhereyouwillputthethingsyouwanttoremember-thelamppostthefruitbowl.Thenineachlocationyouputavisualrepresentationofyourlist-phrasalverbshistoricaldateswhatever-makingthemasstrangeaspossible.Itisthatsimpleanditworks.??6.Thereactionofschoolshasbeenuniformlyenthusiastic.Thepupilsbenefitedenormouslyfromlan’spresentationsaysDrJohnstonheadoftheschoolwhereRobinsonwasspeaking.ldeallyweshouldrunaregularclassinmemorytechniquessopupilscanpickitupgradually.A.GoodresultsB.AnancientskillC.GainingattentionD.MemorytricksE.AlectureonmemorytechniquesF.WaystoimprovememoryParagraph2______.
ProlongingHumanLifeProlonginghumanlifehasincreasedthesizeofthehumanpopulation.Manypeoplealivetodaywouldhavediedofchildhooddiseasesiftheyhadbeenborn100yearsago.Becausemorepeoplelivelongertherearemorepeoplearoundatanygiventime.Infactitisadecreaseindeathratesnotanincreaseinbirthratesthathasledtothepopulationexplosion.Prolonginghumanlifehasalsoincreasedthedependencyload.Inallsocietiespeoplewhoaredisabledortooyoungortoooldtoworkaredependentontherestofsocietytoprovideforthem.Inhuntingandgatheringculturesoldpeoplewhocouldnotkeepupmightbeleftbehindtodie.Intimesoffamineinfantsmightbeallowedtodiebecausetheycouldnotsurviveiftheirparentsstarvedwhereasiftheparentssurvivedtheycouldhaveanotherchild.Inmostcontemporarysocietiespeoplefeelamoralobligationtokeeppeoplealivewhethertheycanworkornot.Wehaveagreatmanypeopletodaywholivepasttheageatwhichtheywanttoworkorareabletowork;wealsohaveroleswhichrequirepeopletoretireatacertainage.Unlessthesepeoplewereabletosavemoneyfortheirretirementsomebodyelsemustsupportthem.IntheUnitedStatesmanyretiredpeopleliveonsocialsecuritycheckswhicharesolittlethattheymustliveinnearpoverty.Olderpeoplehavemoreillnessthanyoungormiddle-agedpeople;unlesstheyhavewealthorprivateorgovernmentinsurancetheymustoftengoonwelfareiftheyhaveaseriousillness.Whenolderpeoplebecomesenileortooweakandilltocareforthemselvestheycreategraveproblemsfortheirfamilies.Inthepastandinsometraditionalculturestheywouldbecaredforathomeuntiltheydied.Todaywithmustmembersofahouseholdworkingorinschoolthereisoftennooneathomewhocancareforasickorweakperson.Tomeetthisneedagreatmanynursinghomesandconvalescenthospitalshavebeenbuilt.Theseareoftenprofit-makingorganizationsalthoughsomearesponsoredbyreligiousandothernonprofitgroups.Whileafewoftheseinstitutionsaregoodmostofthemaresimplydumpinggroundsforthedyinginwhichcareisgivenbypoorlypaidoverworkedandunderskilledpersonnel.Whichofthefollowingbestdescribesthewriter’sattitudetowardmostofthenursinghomesandconvalescenthospitals
TheSmog烟雾 ForoveramonthIndonesiawasincrisis.Forestfiresragedoutofcontrolasthecountrysuffereditsworstdroughtfor50years.Smokefromthefiresmixedwithsunlightandhotdryairtoformacloudofsmog.ThispollutionquicklyspreadandwithindaysitwashangingoverneighbouringcountriesincludingMalaysiaSingaporeandThailand. Whenthesmokecombinedwithpollutionfromfactoriesandcarsitsoonbecamepoisonous有毒的.DangerousamountsofCObecametrappedunderthesmogandpollutionlevelsrose.Peoplewheezed喘息andcoughedastheyleftthehouseandtheireyeswateredimmediately. Thesmogmadeitimpossibletoseeacrossstreetsandwholecitiesdisappearedasgreysoot烟灰coveredeverything.Insomeareaswaterwashosed用胶管浇fromhigh-risecitybuildingstotryandbreakupthesmog. FinallyheavyrainswhichcameinNovemberputoutthefiresandclearedtheair.Buttheenvironmentalcostsandhealthproblemswillremain.ManypeoplefromSouth-EasternAsiancitiesalreadysufferfrombreathinghugeamountsofcarexhaustfumes汽车排放的废气andfactorypollution.Breathingproblemscouldwellincreaseandmanynon-sufferersmayhavedifficultiesforthefirsttime.Wildlifehassufferedtoo.Inlowlandforestselephantsdeerandtigershavebeendrivenoutoftheirhomesbysmog. ButsmogisnotjustanAsianproblem.InfactthewordwasfirstusedinLondonin1905todescribethemixtureofsmokeandthickfog.Fogoftenhungoverthecapital.Sometimesthesmogwassothickandpoisonousthatpeoplewerekilledbybreathingproblemsorinaccidents.About4000Londonersdiedwithinfivedaysasaresultofthicksmogin1952. ManyIndonesiansblamedthegovernmentforthedrought.
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 51
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 65
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 55
{{*HTML*}}SleepingGiant??Rightnowaneruptionisbrewing酝酿inYellowstoneNationalPark黄石国家公园.Sometimeduringthenexttwohoursthepark’smostfamousgeyser间歇泉OldFaithfulwillbegingurgling潺潺地流boilingwaterandsteam.?46???OldFaithfulisnotonlyaspectacularsight;it’salsoaconstantreminderthatYellowstonesitsononeofthelargestvolcanoesintheworld.IfyouhaveneverheardofYellowstone’svolcanoyouarenotalone.?47?Yetithaseruptedthreetimesduringthelast2millionpears.Andoneofthoseeruptionsspewed喷涌enoughvolcanicashandotherdebristoblankethalftheUnitedStates.??Yellowstone’svolcanoissometimescalledasupervolcanoorextremelylargeandexplosivecalderas破火山口volcano.?48?ThissupervolcanoformedoverahotspotanextremelyhotareainEarth’smantle地幔.JohnValleyavolcanoprofessorsaidthatasthecrustmovesacrossahotspotthehotspotmeltsasectionoftheplatemovingoveritformingonevolcanoafteranother.??TheYellowstonehotspotmeltsthickcontinental大陆的crustwhichmaycausecatastrophic灾难性的eruptions.AccordingtoexpertstheeruptionsthatcreatedeachofthethreecalderasinandaroundYellowstoneNationalParkwerelargerthananyothervolcaniceruptioninrecordedhistory.Themostrecenteruptionwhichhappened640000yearsagoproducedatleast1000cubickilometersofashanddebrisandblanketedmostofthewesternhalfoftheUnitedStates.?49???GeologicalevidenceshowsYellowstonehasblownitsstackevery700000yearsorso.IfnatureweretrulythatregularandreliablewewouldbedueforanothereruptionsoonsaidValley.Howevertheseprocessesaresubjecttovariability可变性的sowedon’treallyknowwhenthenexteruptionwillhappen.???50?Itisthevolcanicenergythatpowersthegeysersandhotspringscreatesthemountainsandcanyons峡谷andgeneratestheuniqueecosystemsthatsupportYellowstone’sdiversewildlife.??A.ThreecalderasmakeupmorethanathirdofYellowstoneNationalPark.??B.ThefirstYellowstoneeruption2millionyearsagoreleasedmorethandoublethatamountofashanddebris.??C.Thevolcanoissoinconspicuous不显眼的thatfewpeopleknowitexists.??D.Thenanenormousfountainwillshoothighintotheair.??E.WhiletheactivegeologistprocessesatYellowstonedoposesomerisktothepublictheyalsomakeitauniquetreasure.??F.YellowstoneNationalparkattramstheinterestofgeologiststheworldover.
ByfarthemostcommonsnakeinBritainistheadder.InScotlandinfacttherearenoothersnakesatall.TheadderisalsotheonlyBritainsnakewithapoisonousbite.Itcanbefoundalmostanywherebutpreferssunnyhillsidesandroughopencountryincludinghighground.InIrelandtherearenosnakesatall. Mostpeopleregardsnakebitesasafatalmisfortunebutnotallbitesareseriousandveryfewarefatal:Sometimesattemptsatemergencytreatmentturnouttobemoredangerousthanthebiteitselfwithamateursheroicallybutmistakenlytryingdo-it-yourselfsurgeryandotherunnecessarymeasures. Allsnakeshavesmallteethsoitfollowsthatallsnakescanbitebutonlythebiteoftheadderpresentsanydanger.Britishsnakesareshyanimalsandarefarmorefrightenedofyouthanyoucouldpossiblybeofthem.Theadderwillattackonlyifitfeelsthreatenedascanhappenifyoutakeitbysurpriseandsteponitaccidentallyorifyoutrytocatchitorpickitupwhichitdislikeintensely.Ifithearsyoucomingitwillnormallygetoutofthewayasquicklyasitcanbutadderscannotmoveveryrapidlyandmayattackbeforemovingifyouareveryclose.Theeffectofabitevariesconsiderably.Itdependsuponseveralthingsoneofwhichisthebody-weightofthepersonbitten.Thebiggerthepersonthelessharmfulthebiteislikelytobewhichiswhychildrensufferfarmoreseriouslyfromsnakebitesthanadults.Ahealthypersonwillalsohavebetterresistanceagainstthepoison.VeryfewpeopleactuallydiefromsnakebitesinBritainandthoughthesebitescanmakesomepeopleveryillthereareprobablyjustasmanycasesofbiteshavinglittleornoeffectasthereareofseriousillness. Ifanadderhearsyouapproachingitwillusually.
{{*HTML*}}MemoryTest??1.IamgoingtogiveyoufivetechniquesthatwillenableyoutorememberanythingyouneedtoknowatschoolpromisedlecturerlanRobinsontoahundredschoolchildren.Heslappedhishanddownonthetable.WhenI’vefinishedintwohours’timeyourworkwillbefarmoreeffectiveandproductive.Anyonenotinterestedleavenow.Theentireroomsatstill.??2.RobinsoncallshimselftheMindMagician魔术师.Hespecializesindoingmagictricksthatlooktotallyimpossibleandthenherevealsthattheyinvolvenothingmoremysteriousthangoodold-fashionedtrickery骗术.Ihavealwaysbeeninterestedintricksinvolvingmemory-beingabletoreeloff一口气说出theorderofcardsinapackthatsortofthingheexplains.??3.Robinsonwasalreadylecturingtoschoolsonhismagictechniqueswhenitstruckhimthatstudentsmightfindmemorytechniquesevenmorevaluable.Itwasn’tdifficultareatomoveinotasthestuff’sallthereinbooks.Sohesummarizedeverythingtomakeatwo-hourlectureaboutfivetechniques.??4.Youwanttolearnalistofahundredthings?Athousand?NoproblemsaysRobinson.Thescandalisthateverychildisnottaughtthetechniquesfromthebeginningoftheirschoollife.Theschoolchildrenwhowerewatchinghimthoughtitwasbrilliant.IwishI’dbeentoldthisearliercommentedMarkafterRobinsonhadshownthemhowtoconstructmentaljourneys.??5.Essentiallyyouvisualize想象awalkdownastreetoratriproundaroomandpickthepointswhereyouwillputthethingsyouwanttoremember-thelamppostthefruitbowl.Thenineachlocationyouputavisualrepresentationofyourlist-phrasalverbshistoricaldateswhatever-makingthemasstrangeaspossible.Itisthatsimpleanditworks.??6.Thereactionofschoolshasbeenuniformlyenthusiastic.Thepupilsbenefitedenormouslyfromlan’spresentationsaysDrJohnstonheadoftheschoolwhereRobinsonwasspeaking.ldeallyweshouldrunaregularclassinmemorytechniquessopupilscanpickitupgradually.A.GoodresultsB.AnancientskillC.GainingattentionD.MemorytricksE.AlectureonmemorytechniquesF.WaystoimprovememoryParagraph4______.
TheSmog烟雾 ForoveramonthIndonesiawasincrisis.Forestfiresragedoutofcontrolasthecountrysuffereditsworstdroughtfor50years.Smokefromthefiresmixedwithsunlightandhotdryairtoformacloudofsmog.ThispollutionquicklyspreadandwithindaysitwashangingoverneighbouringcountriesincludingMalaysiaSingaporeandThailand. Whenthesmokecombinedwithpollutionfromfactoriesandcarsitsoonbecamepoisonous有毒的.DangerousamountsofCObecametrappedunderthesmogandpollutionlevelsrose.Peoplewheezed喘息andcoughedastheyleftthehouseandtheireyeswateredimmediately. Thesmogmadeitimpossibletoseeacrossstreetsandwholecitiesdisappearedasgreysoot烟灰coveredeverything.Insomeareaswaterwashosed用胶管浇fromhigh-risecitybuildingstotryandbreakupthesmog. FinallyheavyrainswhichcameinNovemberputoutthefiresandclearedtheair.Buttheenvironmentalcostsandhealthproblemswillremain.ManypeoplefromSouth-EasternAsiancitiesalreadysufferfrombreathinghugeamountsofcarexhaustfumes汽车排放的废气andfactorypollution.Breathingproblemscouldwellincreaseandmanynon-sufferersmayhavedifficultiesforthefirsttime.Wildlifehassufferedtoo.Inlowlandforestselephantsdeerandtigershavebeendrivenoutoftheirhomesbysmog. ButsmogisnotjustanAsianproblem.InfactthewordwasfirstusedinLondonin1905todescribethemixtureofsmokeandthickfog.Fogoftenhungoverthecapital.Sometimesthesmogwassothickandpoisonousthatpeoplewerekilledbybreathingproblemsorinaccidents.About4000Londonersdiedwithinfivedaysasaresultofthicksmogin1952. Indonesiawasincrisisbecauseofthedrought.
Idon'tquitefollowwhatsheissaying.
ProlongingHumanLife Prolonginghumanlifehasincreasedthesizeofthehumanpopulation.Manypeoplealivetodaywouldhavediedofchildhooddiseasesiftheyhadbeenborn100yearsago.Becausemorepeoplelivelongertherearemorepeoplearoundatanygiventime.Infactitisadecreaseindeathratesnotanincreaseinbirthratesthathasledtothepopulationexplosion. Prolonginghumanlifehasalsoincreasedthedependencyload.Inallsocietiespeoplewhoaredisabledortooyoungortoooldtoworkaredependentontherestofsocietytoprovideforthem.Inhuntingandgatheringculturesoldpeoplewhocouldnotkeepupmightbeleftbehindtodie.Intimesoffamineinfantsmightbeallowedtodiebecausetheycouldnotsurviveiftheirparentsstarvedwhereasiftheparentssurvivedtheycouldhaveanotherchild.Inmostcontemporarysocietiespeoplefeelamoralobligationtokeeppeoplealivewhethertheycanworkornot.Wehaveagreatmanypeopletodaywholivepasttheageatwhichtheywanttoworkorareabletowork;wealsohaveroleswhichrequirepeopletoretireatacertainage.Unlessthesepeoplewereabletosavemoneyfortheirretirementsomebodyelsemustsupportthem.IntheUnitedStatesmanyretiredpeopleliveonsocialsecuritycheckswhicharesolittlethattheymustliveinnearpoverty.Olderpeoplehavemoreillnessthanyoungormiddle-agedpeople;unlesstheyhavewealthorprivateorgovernmentinsurancetheymustoften"goonwelfare”iftheyhaveaseriousillness. Whenolderpeoplebecomesenileortooweakandilltocareforthemselvestheycreategraveproblemsfortheirfamilies.Inthepastandinsometraditionalculturestheywouldbecaredforathomeuntiltheydied.Todaywithmustmembersofahouseholdworkingorinschoolthereisoftennooneathomewhocancareforasickorweakperson.Tomeetthisneedagreatmanynursinghomesandconvalescenthospitalshavebeenbuilt.Theseareoftenprofit-makingorganizationsalthoughsomearesponsoredbyreligiousandothernonprofitgroups.Whileafewoftheseinstitutionsaregoodmostofthemaresimply"dumpinggrounds"forthedyinginwhich"care"isgivenbypoorlypaidoverworkedandunderskilledpersonnel. AccordingtothepassagewhichofthefollowingstatementsaboutretiredpeopleintheUnitedStatesistree
TheSmog烟雾 ForoveramonthIndonesiawasincrisis.Forestfiresragedoutofcontrolasthecountrysuffereditsworstdroughtfor50years.Smokefromthefiresmixedwithsunlightandhotdryairtoformacloudofsmog.ThispollutionquicklyspreadandwithindaysitwashangingoverneighbouringcountriesincludingMalaysiaSingaporeandThailand. Whenthesmokecombinedwithpollutionfromfactoriesandcarsitsoonbecamepoisonous有毒的.DangerousamountsofCObecametrappedunderthesmogandpollutionlevelsrose.Peoplewheezed喘息andcoughedastheyleftthehouseandtheireyeswateredimmediately. Thesmogmadeitimpossibletoseeacrossstreetsandwholecitiesdisappearedasgreysoot烟灰coveredeverything.Insomeareaswaterwashosed用胶管浇fromhigh-risecitybuildingstotryandbreakupthesmog. FinallyheavyrainswhichcameinNovemberputoutthefiresandclearedtheair.Buttheenvironmentalcostsandhealthproblemswillremain.ManypeoplefromSouth-EasternAsiancitiesalreadysufferfrombreathinghugeamountsofcarexhaustfumes汽车排放的废气andfactorypollution.Breathingproblemscouldwellincreaseandmanynon-sufferersmayhavedifficultiesforthefirsttime.Wildlifehassufferedtoo.Inlowlandforestselephantsdeerandtigershavebeendrivenoutoftheirhomesbysmog. ButsmogisnotjustanAsianproblem.InfactthewordwasfirstusedinLondonin1905todescribethemixtureofsmokeandthickfog.Fogoftenhungoverthecapital.Sometimesthesmogwassothickandpoisonousthatpeoplewerekilledbybreathingproblemsorinaccidents.About4000Londonersdiedwithinfivedaysasaresultofthicksmogin1952. Theair-pollutionindexwentupto300withinafewdays.
Theworkersinthatfactorymanufacturefurniture.
Nobodycouldfigureoutthisproblem.
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 63
Manyscientistshavebeenprobingpsychologicalproblems.
PuttingPlantstoWorkUsingthepowerofthesunisnothingnew.Peoplehavehadsolar-poweredcalculatorsandbuildingswithsolarpanelsfordecades.Butplantsaretherealexperts:They’vebeenusingsunlightasanenergysourceforbillionsofyears.Ceilsinthegreenleavesofplantsworkliketinyfactoriestoconvertsunlightcarbondioxideandwaterintosugarsandstarchesstoredenergythattheplantscanuse.Thisconversionprocessiscalledphotosynthesis.Unfortunatelyunlessyou’reaplantit’sdifficultandexpensivetoconvertsunlightintostorableenergy.That’swhyscientistsaretakingacloserlookatexactlyhowplantsdoit.Somescientistsaretryingtogetplantsorbiologicalcellsthatactlikeplantstoworkasminiaturephotosyntheticpowerstations.ForexampleMafiaGhirardioftheNationalRenewableEnergyLaboratoryinGoldenColo.isworkingwithgreenalgae.She’stryingtotrickthemintoproducinghydrogeninsteadofsugarswhentheyperformphotosynthesis.Oncetheresearcherscangetthealgaeworkingefficientlythehydrogenthattheyproducecouldbeusedtopowerfuelcellsincarsortogenerateelectricity.Thealgaearegrowninnarrow-neckedglassbottlestoproducehydrogeninthelabduringphotosynthesisplantsnormallymakesugarsorstarches.Butundercertainconditionsalotofalgaeareabletousethesunlightenergynottostorestarchbuttomakehydrogen.Ghirardisays.Forexamplealgaewillproducehydrogeninanairfreeenvironment.It’stheoxygenintheairthatpreventsalgaefrommakinghydrogenmostofthetime.Workinginanairfreeenvironmenthoweverisdifficult.It’snotapracticalwaytoproducecheapenergy.ButGhirardiandhercolleagueshavediscoveredthatbyremovingachemicalcalledsulfatefromtheenvironmentthatthealgaegrowintheywillmakehydrogeninsteadofsugarsevenwhenairispresent.Unfortunatelyremovingthesulfatealsomakesthealgae’scellsworkveryslowlyandnotmuchhydrogenisproduced.Stilltheresearchersseethisasafirststepintheirgoaltoproducehydrogenefficientlyfromalgae.Withmoreworktheymaybeabletospeedthecells’activityandproducelargerquantitiesofhydrogen.Theresearchershopethatalgaewillonedaybeaneasy-to-usefuelsource.TheorganismsarecheaptogetandtofeedGhirardisaysandtheycangrowalmostanywhere:YoucangrowtheminareactorinapondYoucangrowthemintheocean.There’salotofflexibilityinhowyoucanusetheseorganisms./Accordingtothefifthparagraphunderwhatconditionsarealgaeabletousesolarenergytomakehydrogen
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 57
Ihadsomedifficultyincarryingouttheplan.
{{*HTML*}}SleepingGiant??Rightnowaneruptionisbrewing酝酿inYellowstoneNationalPark黄石国家公园.Sometimeduringthenexttwohoursthepark’smostfamousgeyser间歇泉OldFaithfulwillbegingurgling潺潺地流boilingwaterandsteam.?46???OldFaithfulisnotonlyaspectacularsight;it’salsoaconstantreminderthatYellowstonesitsononeofthelargestvolcanoesintheworld.IfyouhaveneverheardofYellowstone’svolcanoyouarenotalone.?47?Yetithaseruptedthreetimesduringthelast2millionpears.Andoneofthoseeruptionsspewed喷涌enoughvolcanicashandotherdebristoblankethalftheUnitedStates.??Yellowstone’svolcanoissometimescalledasupervolcanoorextremelylargeandexplosivecalderas破火山口volcano.?48?ThissupervolcanoformedoverahotspotanextremelyhotareainEarth’smantle地幔.JohnValleyavolcanoprofessorsaidthatasthecrustmovesacrossahotspotthehotspotmeltsasectionoftheplatemovingoveritformingonevolcanoafteranother.??TheYellowstonehotspotmeltsthickcontinental大陆的crustwhichmaycausecatastrophic灾难性的eruptions.AccordingtoexpertstheeruptionsthatcreatedeachofthethreecalderasinandaroundYellowstoneNationalParkwerelargerthananyothervolcaniceruptioninrecordedhistory.Themostrecenteruptionwhichhappened640000yearsagoproducedatleast1000cubickilometersofashanddebrisandblanketedmostofthewesternhalfoftheUnitedStates.?49???GeologicalevidenceshowsYellowstonehasblownitsstackevery700000yearsorso.IfnatureweretrulythatregularandreliablewewouldbedueforanothereruptionsoonsaidValley.Howevertheseprocessesaresubjecttovariability可变性的sowedon’treallyknowwhenthenexteruptionwillhappen.???50?Itisthevolcanicenergythatpowersthegeysersandhotspringscreatesthemountainsandcanyons峡谷andgeneratestheuniqueecosystemsthatsupportYellowstone’sdiversewildlife.??A.ThreecalderasmakeupmorethanathirdofYellowstoneNationalPark.??B.ThefirstYellowstoneeruption2millionyearsagoreleasedmorethandoublethatamountofashanddebris.??C.Thevolcanoissoinconspicuous不显眼的thatfewpeopleknowitexists.??D.Thenanenormousfountainwillshoothighintotheair.??E.WhiletheactivegeologistprocessesatYellowstonedoposesomerisktothepublictheyalsomakeitauniquetreasure.??F.YellowstoneNationalparkattramstheinterestofgeologiststheworldover.
Ican'tputupwithmyneighbor'snoiseanylongerit'sdrivingmemad．
ProlongingHumanLife Prolonginghumanlifehasincreasedthesizeofthehumanpopulation.Manypeoplealivetodaywouldhavediedofchildhooddiseasesiftheyhadbeenborn100yearsago.Becausemorepeoplelivelongertherearemorepeoplearoundatanygiventime.Infactitisadecreaseindeathratesnotanincreaseinbirthratesthathasledtothepopulationexplosion. Prolonginghumanlifehasalsoincreasedthedependencyload.Inallsocietiespeoplewhoaredisabledortooyoungortoooldtoworkaredependentontherestofsocietytoprovideforthem.Inhuntingandgatheringculturesoldpeoplewhocouldnotkeepupmightbeleftbehindtodie.Intimesoffamineinfantsmightbeallowedtodiebecausetheycouldnotsurviveiftheirparentsstarvedwhereasiftheparentssurvivedtheycouldhaveanotherchild.Inmostcontemporarysocietiespeoplefeelamoralobligationtokeeppeoplealivewhethertheycanworkornot.Wehaveagreatmanypeopletodaywholivepasttheageatwhichtheywanttoworkorareabletowork;wealsohaveroleswhichrequirepeopletoretireatacertainage.Unlessthesepeoplewereabletosavemoneyfortheirretirementsomebodyelsemustsupportthem.IntheUnitedStatesmanyretiredpeopleliveonsocialsecuritycheckswhicharesolittlethattheymustliveinnearpoverty.Olderpeoplehavemoreillnessthanyoungormiddle-agedpeople;unlesstheyhavewealthorprivateorgovernmentinsurancetheymustoften"goonwelfare”iftheyhaveaseriousillness. Whenolderpeoplebecomesenileortooweakandilltocareforthemselvestheycreategraveproblemsfortheirfamilies.Inthepastandinsometraditionalculturestheywouldbecaredforathomeuntiltheydied.Todaywithmustmembersofahouseholdworkingorinschoolthereisoftennooneathomewhocancareforasickorweakperson.Tomeetthisneedagreatmanynursinghomesandconvalescenthospitalshavebeenbuilt.Theseareoftenprofit-makingorganizationsalthoughsomearesponsoredbyreligiousandothernonprofitgroups.Whileafewoftheseinstitutionsaregoodmostofthemaresimply"dumpinggrounds"forthedyinginwhich"care"isgivenbypoorlypaidoverworkedandunderskilledpersonnel. Thewriterbelievesthatthepopulationexplosionresultsfrom
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 53
CellPhoneLetsYourSecretOut Yourcellphoneholdssecretsaboutyou.Besidesthenamesand51thatyou’veprogrammedintoittracesofyourDNAlinger逗留onthedeviceaccordingtoanewstudy. DNAisgenetic遗传的materialthat52ineverycell.LikeyourfingerprintyourDNAisuniquetoyou53youhaveanidenticaltwin.ScientiststodayroutinelyanalyzeDNAinbloodsaliva涎唾液orhairleft54atthesceneofacrime.Theresultsoftenhelpdetectivesidentify55andtheirvictims.Yourcellphonecanrevealmoreaboutyou56youmightthink. MeghanJ.McFaddenascientistatMcMasterUniversityinHamiltonOntarioheardaboutacrimeinwhichthesuspectbledontoacellphoneandlaterdroppedthe57ThismadeherwonderwhethertracesofDNAlingeredoncellphones--evenwhennobloodwasinvolved.58sheandcolleagueMargaretWallaceoftheCityUniversityofNewYorkanalyzedtheflip-openphones翻盖手机of10volunteers.Theyusedswabs药签tocollect59tracesoftheusersfromtwopartsofthephone:theoutsidewheretheuserholdsitandthe60whichisplacedattheuser’sear. Thescientistsscrubbed用力擦洗擦净thephonesusingasolutionmademostly61alcohol.TheaimofwashingwastoremovealldetectabletracesofDNA.Theownersgottheirphones 62foranotherweek.Thentheresearcherscollectedthephonesandrepeatedtheswabbingofeachphoneoncemore. ThescientistsdiscoveredDNAthat63tothephone’sspeakeroneachofthephones.BettersampleswerecollectedfromtheoutsideofeachphonebutthoseswabsalsopickedupDNAthatbelongedtootherpeoplewhohadapparentlyalsohandledthephone.64DNAshowedupeveninswabsthatweretakenimmediatelyafterthephoneswerescrubbed.Thatsuggeststhatwashingwon’tremovealltracesofevidencefromacriminal’sdevice.Socellphonescannowbeaddedtothe65ofcluesthatcanclinch确定决定acrime-sceneinvestigation. 59
PuttingPlantstoWorkUsingthepowerofthesunisnothingnew.Peoplehavehadsolar-poweredcalculatorsandbuildingswithsolarpanelsfordecades.Butplantsaretherealexperts:They’vebeenusingsunlightasanenergysourceforbillionsofyears.Ceilsinthegreenleavesofplantsworkliketinyfactoriestoconvertsunlightcarbondioxideandwaterintosugarsandstarchesstoredenergythattheplantscanuse.Thisconversionprocessiscalledphotosynthesis.Unfortunatelyunlessyou’reaplantit’sdifficultandexpensivetoconvertsunlightintostorableenergy.That’swhyscientistsaretakingacloserlookatexactlyhowplantsdoit.Somescientistsaretryingtogetplantsorbiologicalcellsthatactlikeplantstoworkasminiaturephotosyntheticpowerstations.ForexampleMafiaGhirardioftheNationalRenewableEnergyLaboratoryinGoldenColo.isworkingwithgreenalgae.She’stryingtotrickthemintoproducinghydrogeninsteadofsugarswhentheyperformphotosynthesis.Oncetheresearcherscangetthealgaeworkingefficientlythehydrogenthattheyproducecouldbeusedtopowerfuelcellsincarsortogenerateelectricity.Thealgaearegrowninnarrow-neckedglassbottlestoproducehydrogeninthelabduringphotosynthesisplantsnormallymakesugarsorstarches.Butundercertainconditionsalotofalgaeareabletousethesunlightenergynottostorestarchbuttomakehydrogen.Ghirardisays.Forexamplealgaewillproducehydrogeninanairfreeenvironment.It’stheoxygenintheairthatpreventsalgaefrommakinghydrogenmostofthetime.Workinginanairfreeenvironmenthoweverisdifficult.It’snotapracticalwaytoproducecheapenergy.ButGhirardiandhercolleagueshavediscoveredthatbyremovingachemicalcalledsulfatefromtheenvironmentthatthealgaegrowintheywillmakehydrogeninsteadofsugarsevenwhenairispresent.Unfortunatelyremovingthesulfatealsomakesthealgae’scellsworkveryslowlyandnotmuchhydrogenisproduced.Stilltheresearchersseethisasafirststepintheirgoaltoproducehydrogenefficientlyfromalgae.Withmoreworktheymaybeabletospeedthecells’activityandproducelargerquantitiesofhydrogen.Theresearchershopethatalgaewillonedaybeaneasy-to-usefuelsource.TheorganismsarecheaptogetandtofeedGhirardisaysandtheycangrowalmostanywhere:YoucangrowtheminareactorinapondYoucangrowthemintheocean.There’salotofflexibilityinhowyoucanusetheseorganisms./WhatisNOTtrueofalgae
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