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如图,在△ABC中,已知,AB=AC=6,BC=10.E是C边上一动点(E不与点B、C重合),△DEF≌△ABC.其中点A,B的对应点分别是点D、E,且点E在运动时,DE边始终经过点A,设EF与AC...
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如图△ABC中∠C.=90°AC=BCAD是∠CAB的平分线DE⊥AB于E.已知AB=10cm则△D
如图在△ABC中AC=BC∠C.=90°AD是△ABC的角平分线DE⊥AB垂足为E.1已知CD=4c
如图已知△ABC中AB=10AC=8BC=6DE是AC的垂直平分线DE交AB于点D连接CD则CD=
3
4
4.8
5
如图△ABC中已知BC=12AB的垂直平分线交AB于点D.交AC于点E.△BCE的周长为28则AC的
如图△ABC中∠C.=90°AC=BCAD是∠CAB的平分线DE⊥AB于E.已知AB=10cm则△D
如图在Rt△ABC中∠C=90°BD平分∠ABC与AC交于点D.点O.是AB上一点⊙O过B.D.两点
如图已知在△ABC中AB=AC=10DE垂直平分AB垂足为EDE交AC于D若△BDC的周长为16则B
已知如图点D.在△ABC的BC边上AC∥BEBC=BE∠ABC=∠E.求证AB=DE.
已知:如图ΔABC中∠ABC=2∠C.BD平分∠ABC.求证:AB·BC=AC·CD.
如图在Rt△ABC中∠C.=90°∠ABC的平分线交AC于点D.点O.是AB上一点⊙O过B.D.两点
如图已知在△ABC中AB=ACM.是边BC的中点D.E.分别是边ABAC上的点且BD=CE求证MD=
已知如图△ABC中AB=AC=10D.是BC边上的任意一点分别作DF∥AB交AC于F.DE∥AC交A
已知如图△ABC中AB=AC以AB为直径的⊙O.交BC于点P.PD⊥AC于点D.1求证PD是⊙O.的
如图△ABC中AB=ACAD是∠BAC的平分线已知AB=5AD=3则BC的长为
5
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10
如图已知在△ABC中AB=ACBD是AC边上的中线AB=13BC=101求△ABC的面积2求tan∠
已知如图△ABC中AB=AC以AB为直径的⊙O.交BC于点P.PD⊥AC于点D.1求证PD是⊙O.的
如图△ABC中∠C.=90°AC=BCAD是∠CAB的平分线DE⊥AB于E.已知AB=10cm则△D
已知如图△ABC中∠C.=90o点O.为△ABC的三条角平分线的交点OD⊥BCOE⊥ACOF⊥AB点
2、2、2
3、3、3
4、4、4
2、3、5
在△ABC中点D.E分别是边ABAC的中点已知BC=10求DE的长
3
4
6
5
已知如图△ABC中∠C.=90°点O.为△ABC的三条角平分线的交点OD⊥BCOE⊥ACOF⊥AB点
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下列具有细胞壁但成分不含纤维素的是A.乳酸菌 B.洋葱根尖细胞 C.噬菌体 D.马蛔虫受精卵
如图在Rt△ABC中∠ACB=90°tanB=BC=12cm点N从点C出发沿CB方向以1cm/s的速度运动点N到达点B时停止运动以CN为边在BC的上方作正方形CNGH正方形CNGH的边NG所在直线与线段AB交于点Q设运动时间为ts.1当t为何值时QN的长为6cm2当点G落在线段AB上时求t的值时3设正方形CNGH与Rt△ABC重叠部分的图形的面积为S.求出S关于t的函数关系式并写出自变量t的取值范围.4连结CQ当t为何值时△CQB是等腰三角形
Traditionallyweusuallygetageneralimpressionof1strangersstrangerbythewaytheyshakehandstalkorwalk.Howeverintheageofsocialnetworkingfirstimpressionsaresometimesmade2bylookingattheirprofilephotosonsocialplatformslikeTwitterorWeChat. Thesesocialimagessayalotaboutourpersonalityaccordingtoarecentstudyin3whichresearchersusedasoftwaretoanalyzetheprofilephotostofindoutwhethertherewasaconnectionbetweenaperson'spersonalityandhisprofilephoto. Theresultrevealsthatopen﹣mindedpeoplearemorelikely4toposeposewithanobjectintheirprofilephotos.Their5excitedexcitefacescantellhowmuchtheyenjoytheirexperiences.Meanwhileneurotic神经质的peopletendtochoosephotosofobjectsratherthanselfiestoavoid6lookinglooktoomiserablebecauseofthestrongsocialpracticeagainstasadorangry7appearanceappearinprofilephotos. Apartfromtheobjectsinprofilephotosthecolorsusedinthemalsoshow8howoutgoingtheowneris.Forexampleextroverts性格外向者9arefoundfindtohavethemostcolorfulprofileimagesastheywanttoemphasizetheirpersonality. Nexttimechoosingaprofilephotomaybeweshouldask10ourselveswefirstwhatkindofimagewe'dliketoconvey.Afterallapictureisworthathousandwords.
下列是表示①②③④四个框图内所包括生物的共同特征的叙述正确的是 A.框图①内都是原核生物都有成形的细胞核B.框图②内的生物都不含叶绿素都是异养型C.框图③内的生物都具有细胞结构且都有细胞壁D.框图④内都是自养生物且都含有核糖体
ThefirstThursdayinMayisWorldPasswordDaybutdon'tbuyacakeorsendcards.ComputerchipmakerIntelcreatedtheeventasanannualreminder.1F. Thepurposeofapasswordistolimitaccesstoinformation.Havingaverycommonorsimpleonelikeabcdeforevennormalwordslikepasswordisbarelyanysecurityatall.2E.Hackers'passwordcrackingtoolstakeadvantageofthislackofcreativityandgetinouraccountseasily.Moreexperienceduserswouldchoosealesscommonpassword.Howevertheymightstillfallvictimtocrackingsoftware. 3CAsecurepasswordisallthatstandsbetweenusandacybercriminal.Itshouldbeuniqueandcomplexwhichahackercan'teasilyguessorcrack.Thebestpasswordsaresupposedtobeatleast15characterslongandfullofrandomnumbersandletters.Howeveralongpasswordmeansacomplicatedprocesstologintoawebsite.4G.Youmaywanttowriteitdownbutitisnotsuggestedduetorisk. Thenwhatshouldwedo5B.YoucanchooseaphrasesuchasIwanttogotoEngland.Nextconvertittoanabbreviation缩略语byusingthefirstlettersofeachwordandchangingthewordtoto2.Thenyougetfollowingpasswordphraseiw2g2e.Youcanmakeitevenmorecomplexbyaddingpunctuationspacesorsymbols%iw_2g2e!@.Itismucheasiertorememberandsafer. Can'twaittotryLet'ssaygoodbyeto666666andchangeyourpasswordrightnow. A.Whatdonetworksecurityexpertsdo B.Tryusingshortenedphrasesforpasswords C.Howcanweensurethesafetyofapassword D.Changingpasswordregularlyisaneffectiveway E.Thatislikeclosingadoorbutnotactuallylockingit F.Itisusedtosayfarewelltopopularpasswordslike123456 G.Anditisalsodifficultforustorememberalongirregularpassword
DearDurhammers Durhamhasbeenyourhomeinthepastthreeyears.Thisisanappropriatemomentintimetoinviteyouasagroupoftouristsinthisspecialexploration.WewouldalsoliketocongratulateyouonyourforthcomingtransitionfrombeingaDurhammertoamemberofsociety.Pleaseseeinformationbelowonoffersandactivitiestoassistwithplanningyourcomingcelebrations. ViewdetailsofspecialoffersforWinterAssemblyat http://www.dur.ac.uk/ceremonies/congregation/offers/ ●SignuptokeepintouchwithDurhamUniversityandgetagoodybagsponsoredbytheALUMNIteam. ●20%discountonpre﹣orderedDurhamUniversityMerchandisewiththeticketcodeWGRADUATE2019Oryouhavetopaythefullpriceattheshop. ●Pre﹣orderyourphotographsandreceiveadiscountedrate. ●FreeentrytotheexhibitionsatPalaceGreenLibraryforyouandyourguestswithtickets. ●Purchaseadiplomacontainertokeepyourdegreecertificatesafe.Pleasecheck https∥www.dur.ac.uk/student.registry/qualifications/order/ ●DetailsofcelebrationeventsbeingheldinDepartmentsandCollegesarepublishedat https∥www.dur.ac.uk/ceremonies/congregation/celebrations/ InformationonthehighlightofthecelebrationincludingbutnotlimitedtotheopportunitytogooutforBBQandcampingatBotanticGardenispublishedat https∥www.dur.ac.uk/campusperks/whatsnewon/ceremonies/ Wealsohopeverymuchthatyouwillcomeandmeetusandcolleaguesattheceremonywhichisatraditionalandmagnificentpublicpresentationofyourdiplomaandawardanditisalwaysmemorableandfun.Youwillhavealreadyreceivedaformalemailinvitationbutthisisjusttosaythatwehopetomeetyouthereandcongratulateyouinperson. Yourssincerely SirThomasAllen 1WhoistheletterintendedforB A.Visitorsexploringthecampus. B.GraduatesfromDurhamUniversity. C.ColleaguesinDurhamUniversity. D.OrganizersoftheALUMNIGroup. 2Wherecanyoucheckdetailsoftheoff﹣campuscelebrationeventsD A.www.dur.ac.uk/ceremonies/congregation/offers/ B.www.dur.ac.uk/student.registry/qualifications/order/ C.www.dur.ac.uk/ceremonies/congregation/celebrations/ D.www.dur.ac.uk/campusperks/whatsnewon/ceremonies/ 3WhichofthefollowingitemsarefreeofchargeA A.Goodybags. B.Diplomacontainers. C.Pre﹣orderedphotographs. D.Librarycards.
下列有关巴氏芽孢杆菌的叙述正确的是A.巴氏芽孢杆菌有核膜B.巴氏芽孢杆菌含有染色体C.巴氏芽孢杆菌含有DNAD.巴氏芽孢杆菌无细胞器但能完成复杂的生命活动
下图为HIV和T4噬菌体结构示意图请据图判断下列说法正确的是 A.两种病毒都含有蛋白质不含有水B.两种病毒的宿主细胞相同C.两种病毒都能在细胞外独立生存D.HIV的宿主细胞是上呼吸道细胞和肺泡细胞
二次函数y=x2+4x+c的对称轴是
关于蓝藻的说法不正确的是
Evenforafirst﹣timevisitortoChinaitisimpossibletoignorethepopularityofQuick﹣ResponseQRcodes.Thesesquare﹣shapedblack﹣and﹣whitesymbolsinWeChatorAlipaywhereQRcodesarescannedtoaddnewfriendsormakepayments. TheQRCodesystemoriginatedinJapan.TheengineerMasahiroHarafeltthelimitationoftheone﹣dimensionbarcodeinuseandthusdevelopedtheQRcodeswhichcouldcarrydatahorizontallyandvertically.QRcodescouldholdmuchmoreinformationthanbarcodeduetotheirextradimension.InadditionQRcodeshavelargerdatacapacitysmallerprint﹣outsizeandhigherresistancetodirtanddamagewhichmakethemwidelyappliedinmanyotherapplications. ThoughthetechnologyofQRcodesiscomplicatedwecaneasilycreateourownQRcodeswiththehelpofQRcodegeneratorsmanyofwhichareavailableonlineforfree.UserscouldenterthedatatheywishtheQRcodetodisplayandthegeneratorturnsitintoasymbolthatcanbeprintedordisplayedinelectronicform.TheprocessofcreatingQRcodescouldbereallyfunwhenwecustomisethedesignofthecodesaccordingtoourspecificneeds.Forinstancewecanadjustthecoloraddalogoandcreatesocialoptionsetc.Moreoverdynamic动态的QRcodesarealsoavailable.TheyaremorevariousthanstandardQRcodesbecausetheyallowuserstoeditdataenteredpreviouslywhereasdatainstandardQRcodescannotbeeditedonceprinted.Plusdon'tlimityourQRcodetoonemobilescanner.Anyonecanscanyourcodewithanyreader.Alowerbarriertoentrymakessuccessmorelikelyforyouandtheuser. MeanwhilewemustalsorecognizethevulnerabilityofQRcodes.DuetoitseasyaccesscriminalscanstealsimplybyreplacingtheQRcodeswiththeirownroutingcashintotheirownbankaccounts.HenceweshouldallbecomemoreconscioustowardsvirtualmoneytransactionsthroughQRcodesandparticipateinadditionalsecuritymeasures. 1WhichofthefollowingisNOTafunctionofQRcodesB A.Datastorage. B.Scanningreader. C.Socialnetworking. D.Mobilepayment. 2Whyisbarcodementionedinparagraph2C A.Tointroducethemaintopic. B.Toshowtheauthor'sattitude. C.TohighlightthefeaturesofQRcodes. D.Toaddsomebackgroundknowledge. 3Whichofthefollowingbestexplainsvulnerabilityunderlinedinparagraph4B A.Threat. B.Weakness. C.Difficulty. D.Simplicity. 4WhichistrueaboutQRcodesaccordingtothetextD A.TheywerefirstusedinChina. B.Thegeneratorschargetheusersalot. C.DataeditingispossibleinprintedQRcodes. D.MorescanningdevicesareavailableinreadingQRcodes.
下列关于真核生物原核生物和病毒的叙述中有几项正确①乳酸菌青霉菌大肠杆菌都属于原核生物②乳酸菌酵母菌都含有核糖体和DNA③T2噬菌体一种病毒的繁殖只在宿主细胞中进行因为只有核糖体一种细胞器④细胞没有叶绿体就不能进行光合作用A.1项 B.2项 C.3项 D.4项
据新华网华盛顿2017年9月18日消息美国医学会杂质·内科学卷18日刊载的一项研究显示如果艾滋病病毒携带者在接受抗逆转录药物治疗时还吸烟那么他们死于肺癌的可能性比死于艾滋病的可能性会高出10倍左右.下列相关叙述正确的是A.艾滋病病毒在活细胞外能大量增殖B.艾滋病病毒仅含有核糖体这一种细胞器C.艾滋病病毒携带者在接受抗逆转录药物治疗时不需戒烟D.戒烟预防肺癌应成为护理艾滋病病毒携带者的重要措施
下列有关细胞的叙述正确的是A.病毒是一类具有细胞结构的生物B.蓝藻细胞具有细胞核且DNA分子呈环状C.人体所有细胞的形态结构相同D.最早的生命是具有细胞结构的单细胞生物
下列概念依次与图中abcd相对应的一组是 A.真核生物动物植物真菌 B.生物真核生物原核生物真菌C.系统生命系统生态系统群落 D.原核生物细菌蓝藻病毒
中秋节前夕某公司的李会计受公司委派去超市购买若干盒美心月饼超市给出了该种月饼不同购买数量的价格优惠如图折线ABCD表示购买这种月饼每盒的价格y元与盒数x盒之间的函数关系.1当购买这种月饼盒数不超过10盒时一盒月饼的价格为元2求出当10<x<25时y与x之间的函数关系式3当时李会计支付了3600元购买这种月饼那么李会计买了多少盒这种月饼
下列有关组成生物体化学元素的叙述正确的是A.碳元素在生物体中的含量一定是最多的B.动物和植物所含化学元素的种类和含量相同C.组成生物体的化学元素在自然界中很难找到D.CHON都是大量元素
请分析并回答问题1细菌细胞壁的主要成分是肽聚糖青霉素抑制肽聚糖的合成从而起到抑制细菌生长的作用.艾滋病病人能否通过注射青霉素抑制病毒的增殖为什么.2如图中表示在低倍显微镜视野中观察到的细胞请据图回答①图中将装片向方移动可将上图所示视野中细胞移到视野正中央.②用显微镜观察某标本时已知目镜的放大倍数为10×物镜的放大倍数为40×则物像的放大倍数为.A.长度宽度均放大400倍 B.面积放大了400倍C.长度或宽度放大40倍 D.标本的体积放大400倍
下列有关细胞学说说法正确的是A.德国科学家施莱登和施旺是发现了细胞并创立细胞学说B.细胞学说指出生物是由细胞及其产物构成并由细胞发育而来C.细胞通过分裂产生新细胞是对细胞学说的修正D.细胞学说揭示了细胞和生物体结构都具有统一性和多样性
下列关于系统的叙述正确的是A.病毒能够繁殖是最基本的生命系统B.系统是指彼此间相互作用相互依赖的组分有规律地结合而形成的整体C.生活在一定区域的所有生物构成生态系统D.生殖器官和营养器官构成植物的系统
如图在平面直角坐标系中抛物线y=x2经过平移得到抛物线y=x2-3x其对称轴与两段抛物线所围成的阴影部分的面积为
分式有意义则x的取值范围是
Itisbecomingincreasinglyimportantforresearcherstocloselymonitorouroceanlife.HoweverobservingseacreaturesUpcloseisalmostimpossiblesincehumanpresencescaresthem.NowthankstoTheSoftRoboticFishalsoknownasSoFiresearchersmaybeabletokeepacloseeyeontheseacreatures. BuiltbyMITComputerScienceandArtificialIntelligenceLaboratoryCSAILthewhitere﹣mote﹣controlledrobotresemblestherealfishcompletewithatailthatwavesfromsidetoside.ThoughnotthefirstautonomousunderwatervehicleAUVcreatedtomonitortheoceanSoFiset﹣tlesmanyoftheproblemsthathaveblockedtheusefulnessofthepreviousrobotfish. PreviousAUVshavehadtobelinkedtoboatsbecauseradiofrequencycommunicationsdon'tworkwellunderwater.ToovercometheproblemDirectorofdieCSALLDanielaRusandherteamusedsoundwaves.ThetechnologycantravelgreaterdistancesallowingdiverstopilotSoFifromupto50feetaway. AlsolimitingtheusefulnessoftraditionalAUVsistheriskofcollision.Withtheoutsidemadeofsoftsilicone硅树脂rubberandflexibleplasticthatkeepsitsinbuiltelectronicsdrySoFiposesnosuchdanger.Collisionavoidanceoftenleadstounnecessarymovementsincetherobothastosettleforacollision﹣freepathsaysRus.Incontrastasoftrobotisnotonlymorelikelytosurviveacollisionbutalsocoulduseitasinformationtoformamoreworkablemovementplannexttimearound. DuringtestdivesSoFimovedalongsidetheoceanlifeatdepthsof50feetforupto40minutesatatimetakingphotosandmakingvideos.Theresearcherssaysometimesthefishwouldswima﹣longsidethestrange﹣lookingrobot﹣fishoutofcuriositywhileatothertimestheytooknonoticeofitsexistence. WhileSoFipresentlyonlyrecordsvideofutureversionswillincludesensors.Theresearchersalsohopetomakeitmoreautonomous.WeimaginesomedayitmighthelpusuncovermoresecretsfromtheamazingunderwaterworldthatweknowsolittleaboutsaysRus. 1WhatdoesthewaterthinkofSoFi? A.Itmakesoceancreaturedetectioneasier. B.ItisthefirstAUV. C.Itiscloselycontrolled. D.Itscaresseaanimalsaway. 2Accordingtopara3whichofthefollowingisture? A.Soundwavestravelfasterthanradio B.Soundwavesworkbetterthanradiounderwater. C.PreviousAUVsusesoundAvavestocommunicate. D.AboattravelsalongwithSoFionthewater. 3HowdoesSoFidealwithcollision? A.Itcanbenefitfaromitsinbuiltelectronics. B.Itcanavoidextramovement. C.Itcansmartlyadjustitsmovementplan. D.Itissetforacollision﹣freepath. 4WhatwillhappentoSoFiinthefuture? A.SoFicanrecordvideos. B.SoFiwillgoinvisible. C.SoFiwillbefreefromexternalcontroL D.SoFiwillbeequippedwithsmartdevices.
IhavelearnedsomethingaboutmyselfsinceImovedfromLongIslandtoFloridathreeyearsago.EventhoughIownahomeinPortSt.LuciejustminutesfromtheoceananuncontrollableurgewellsuptoreturntoLongIslandevenasothersmaketheirwaysouth.IguessIamasnowbi俎stuckinreverse.InsteadofenjoyingFlorida'smildwintersIwillinglyendurethesevereweatheronLongIslandtheplaceIcalledhomefor65years. I'mlikeamigratorybirdthathaslostitssenseoftiminganddirectionmywingsflappingagainstseason. Sowhatmakesmeflyagainstthetideofsnowbirds?TheanswerhasalottodowithmyreluctancetogiveupthethingsthatdefinewhoIam.OnceIhearthatthetemperatureonLongIslandhasdippedintotherangeof40to50degreesIbegintolongforthesightandcracklingsoundofawoodfire.Ialsolongforthebrightdisplayo£colors﹣firstinthe£alltreesandtheninthelimitsaroundhomesandatRockefellerCenter.Floridiansdecoratetoobutcan'tcreatethespecialfeelofaNewEnglandwinter. IsupposethebiggestreasonwhyItelumistocelebratetheholidayswithpeopleIhaven'tseeninmonths.WhatcouldbebetterthansittingwithfamilyandfriendsforaThanksgivingturkeydinnerorwatchingneighbors'childrenexcitedlyopengiftsonChristmas?Eventhefirstsnowfallseemsspecial.Iespeciallyenjoyseeingabrightredbirdsettlingonasnow﹣coveredbranchMywifeandIspendwintersataretirementcommunityinRidgeandI'mgratefulthatIdon'thavetoshovel. WhilethesesimplepleasuresarenotuniquetoLongIslandtheyaresomeofthereasmiswhyIcomeback.Whosaysyoucan'tgohome? 1WhatdoestheunderlinedwordsnowbirdinParagraph1referto? A.Apersonspendingwinterinawarmerclimate. B.Abirdseenchieflyinwinter. C.Apersonpermanentlylivinginaforeigncountry. D.Abirdflyingtothesouthinwinter. 2What'sthedifferencebetweenFloridaandLongIsland? A.WintersinLongIslandaremilder. B.ThesnowbirdsinLongIslandarerarer. C.WeatherinLongIslandisseverer. D.LongIslandisnearertotheocean. 3WhatdidtheauthormissmostwhenhewasinFlorida? A.Thecoldtemporature. B.Thecolorfullightdisplay. C.Thefamilygathering. D.Thewinterlandscape. 4What'stheauthor'spurposeinwritingthetext? A.Topraisethebeautyandwarmthofhishometown. B.Todescribehisdreamtobeafreebird. C.Toexplainthereasonsformovingfromhishometown. D.Toexpresshisfeelingofmissinghishometown.
假定你是李华你的朋友Daniel给你发邮件说他想在美国办个主题为'中国风'的摄影展他想来你的家乡收集素材.请给他回一封邮件内容包括1.表示欢迎2.提出建议3.安排接机.注意1.词数100左右2.可以适当增加细节以使行文连贯.
下列关于念珠藻的叙述中不正确的是A.不具有细胞壁 B.DNA分子呈环状C.没有核膜包被 D.其细胞质内只有核糖体一种细胞器
使用普通光学显微镜观察水中微生物若发现视野中微生物向图1所示方向游走请问应该把载玻片向图2所示的哪个方向移动
同一个装片在不同放大倍数的显微镜下观察效果不同下列相关叙述中不正确的是
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