首页
试卷库
试题库
当前位置：
X题卡
>
所有题目
>
题目详情
在极坐标系中，O为极点，点M（ρ0，θ0）（ρ0＞0）在曲线C：ρ=4sinθ上，直线l过点A（4，0）且与OM垂直，垂足为P． （1）当θ0=时，求ρ0及l的极坐标方程； （2）当M在C上运动...
查看本题答案
包含此试题的试卷
高三下学期数学《》真题及答案
点击查看
你可能感兴趣的试题
在平面直角坐标系xOy中已知曲线C.a为参数在以原点O.为极点x轴的非负半轴为极轴建立的极坐标系中直
选修4—4坐标系与参数方程 在直线坐标系xOy中曲线C1的参数方程为t为参数a＞0在以坐标原点为极
在直角坐标系xOy中以原点O.为极点x轴的正半轴为极轴建立极坐标系.若P.点为直线ρcosθ-ρsi
在直角坐标系中中曲线C1的参数方程为t为参数在以O.为极点x轴的正半轴为极轴的极坐标系中曲线C2的极
23.在直角坐标系xOy中圆C.的参数方程为θ为参数.1以原点为极点x轴正半轴为极轴建立极坐标系求圆
选修4—4坐标系与参数方程 在直线坐标系xOy中曲线C1的参数方程为t为参数a＞0在以坐标原点为极
在直角坐标系xOy中直线l经过点P.－10其倾斜角为α.以原点O.为极点以x轴非负半轴为极轴与直角坐
在极坐标系中曲线C.的极坐标方程为ρsin2θ﹣cosθ=0点.以极点O.为原点以极轴为x轴正半轴建
在平面直角坐标系xOy中圆C.的参数方程为在以原点O.为极点x轴的非负半轴为极轴建立的极坐标系中直线
在平面直角坐标系中圆M的参数方程为为参数以为极轴O为极点建立极坐标系在该极坐标系下圆N是以点为圆心且
在平面直角坐标系xOy中曲线C的参数方程为θ为参数．以坐标原点O为极点x轴的正半轴为极轴建立极坐标
在直角坐标系xoy中曲线C.的参数方程为θ为参数以坐标原点为极点以x轴的正半轴为极轴建立极坐标系.Ⅰ
在直角坐标系xOy中直线l的参数方程为为参数若以O.为极点x轴正半轴为极轴建立极坐标系曲线C.的极坐
已知平面直角坐标内两点A02B−40AB的中点是M以原点为极点x轴正半轴为极轴建立极坐标系则M的极坐
在直角坐标系xOy中圆C.的参数方程为α为参数以坐标原点为极点x轴正半轴为极轴建立极坐标系.1求圆C
在以O为极点的极坐标系中直线l的极坐标方程是ρcosθ﹣2=0直线l与极轴相交于点M以OM为直径的
ρ=2+cosθ
ρ=2sinθ
2ρ=cosθ
ρ=2cosθ
在极坐标系中以极点为坐标原点极轴为x轴正半轴建立直角坐标系点M.2的直角坐标是
（2，1）
（
，1）
（1，
）
（1,2）
以直角坐标系的原点O.为极点x轴的正半轴为极轴建立极坐标系已知点P.的直角坐标为1－5点M.的极坐标
在直角坐标系xOy中直线l经过点P-10其倾斜角为α以原点O.为极点以x轴非负半轴为极轴与直角坐标系
在平面直角坐标系xOy中曲线C的参数方程为θ为参数．以坐标原点O为极点x轴的正半轴为极轴建立极坐标
热门试题
更多
已知集合A={x|x＞﹣1}B={x|x＜2}则A∩B=
图1是某学习小组学生数学考试成绩的茎叶图1号到16号的同学的成绩依次为A1A2…A16图2是统计茎叶图中成绩在一定范围内的学生情况的程序框图那么该程序框图输出的结果是
已知三棱锥的三视图如图所示则该三棱锥外接球的表面积为
如图长方体ABCD﹣A1B1C1D1的底面ABCD是正方形点E在棱AA1上BE⊥EC1． 1证明BE⊥平面EB1C1 2若AE=A1EAB=3求四棱锥E﹣BB1C1C的体积．
阅读下面短文根据所给情节进行续写使之构成一个完整的故事.WhenIarrivedat6a.m.inthelargehospitalkitchenRosewasalreadycheckingnametagsonthetrays托盘.HiI'mJanet.'ItriedtosoundcheerfulalthoughIalreadyknewRose'sreputationforbeingimpossibletoworkwith.'I'mscheduledtoworkwithyouthisweek.'Rosestoppedwhatshewasdoingandpeeredoverherreadingglasses.Icouldtellfromherexpressionshewasn'tpleasedtosecastudentworker.'Whatdoyouwantmetodo?Startthecoffee?'Iasked.Rosecoldlynoddedandwentbacktocheckingnametags.Ifilledthe40﹣cuppotwithwaterandbeganmakingthecoffeewhenRoseyelled'That'snotthewaytomakecoffee.'Shesteppedinandtookover.NothingIdidpleasedher.Allmorninghereagleeyesmissednothingandhersharpwordshurt.TotallyexhaustedItrudgedthesixblockshomelatethatJuneafternoon.AsathirdyearuniversitystudentworkingmywaythroughschoolIhadneverbeforemetanyonelikeRose.FightingbacktearsIwrestledwithmydilemmaaloneinmyroom.'WhatshallIdo?'Theanswercaughtmecompletelybysurprise.IneededtoloveRose.WorkingwithRosethenextmorningIignoredthehurtfulremarksthrowninmydirectionanddidthingsRose'swayasmuchaspossible.AsIworkedIsilentlybegantosurroundRosewithawarmblanketoflove.Overthenextfewdaysanamazingthingbegantohappen.MyfocusshiftedfromwhatshewasdoingtomeandIstartedseeingRoseasthehurtingpersonshewas.Thenhericytensionbegantomeltaway.Throughouttherestofthesummerwehadnumerousopportunitiestoworktogether.Eachtimesheseemedtrulyhappytoseeme.Herbitternessgavewayasshestartedopeningup.AsIworkedwiththislonelywomanIlistenedtohersomethingnooneelsehaddone.Ilearnedthatshewasburdenedbyelderlyparentswhoneededhercareandherownhealthproblems.ThedaysslippedbyquicklyasIfinishedthelastseveralweeksofmysummerjob.Isoonwouldbereturningasafull﹣timeuniversitystudentandsaygoodbyetoRose.注意1.所续写短文的词数应为150左右2.应使用5个以上短文中标有下划线的关键词语3.续写部分分为两段每段的开头语已为你写好4.续写完成后请用下划线标出你所使用的关键词语.Paragraph1OnedaywhileIwasworkingaloneinoneofthehospitalkitchensRoseenteredtheroom.Paragraph2AlthoughIneversawRoseagainIstillrememberhervividly.
Neitherstyleofthinkingisbetterorworsethantheotherthey'rejustdifferentasProfessorAnkushChopraexplains.Tobeagreatartistmusicianorbig﹣picturethinkerholisticthinkingisimportant﹣it'saboutcontextandintuition直觉isimportant.Manycareerslikethoseinscienceorlawrewardanalyticthinkingwhichlooksatpartsandunitsandisspecificandlogical.Ofcoursethemostsuccessfulpeoplewillbeabletodobothkindsofthinkingthoughgenerallyholisticthinkinglinkedtocreativityismoredifficulttoteachthananalyticthinking. Sothosepeoplewhoareanalyticthinkerswillseeapriceof＄1.99bylookingatthesinglenumbersandwillprioritizethefirstnumberwhenitcomestoprice.Holisticthinkerstendtoviewallpricenumbersasawholeandarelesslikelytobeaffectedbythenine﹣endingpriceeffectLingjiangLoraTuPh.D.professorofmarketingatBaylorandastudy'sleadauthortoldPhys.org. Howeverthatthetypeofthinkingallowsholisticthinkerstoseethewholeratherthanthepartsgoesoutthewindowwhenthey'restressedordistracted分心的. Ourfindingssuggestthatregardlessofconsumers'thinkingstylenine﹣endingpricesaremostlikelytobeeffectiveinsituationsthatoveruseconsumers'resourcessuchaswhenshoppersaretime﹣pressuredatthecheckoutcounterordistractedbybackgroundmusicoroccupiedwithaninteractiveproductdemonstrationTusaid. Thisstudywasdonewiththeideathatmarketersshouldknowaboutthesedifferencesinthinkingstyleandkeeptheminmindwhenthey'repricingthingsfordifferenttypesofpeople.Butanyonewhobuysthingscanbenefittoobyfiguringoutwhatkindofthinkeryouareandthenkeepingthatinmindwhenthesignsshowsalewithaloudnoise!﹣andremindingyourselfthatnobodymakesthebestdecisionswhenthey'redistracted. 1Whichofthefollowingcanbethebestexampleofholisticthinking? A.OnlyifthewholethingmakessensecanJackconcentrateondetails. B.InAmericanshopsyoucanfindmanythingswithnine﹣endingprices. C.Jackkeptonworkingononethingandfinallyachievedgreatsuccess. D.Understandingeachparagraphleadstounderstandingthewholepassage. 2TheunderlinedwordprioritizeinPara.2mostprobablymeans. A.takenonoticeof… B.treat…equally C.thinkof…thetrickiest D.consider…themostimportant 3Accordingtothepassageaconsumershouldrememberthat. A.thenine﹣endingpricescanequallyaffectanytypeofconsumer B.pricingthingsfordifferenttypesofpeoplebenefitscustomers C.backgroundmusicisn'talwaystocreateapleasantatmosphere D.it'simpossibletoaffecthimevenifhe'sdistractedorstressed 4Fromthepassageweknowthat. A.differentthinkingstylescreatedifferentpricingsystems B.preferenceofpricingsystemcanindicatethinkingstyle C.holisticthinkingsomewhatoutweighsanalyticthinking D.bothstylesofthinkingcannotbebeneficialtoonecareer
某行业主管部门为了解本行业中小企业的生产情况随机调查了100个企业得到这些企业第一季度相对于前一年第一季度产值增长率y的频数分布表． 1分别估计这类企业中产值增长率不低于40%的企业比例产值负增长的企业比例 2求这类企业产值增长率的平均数与标准差的估计值同一组中的数据用该组区间的中点值为代表．精确到0.01 附≈8.602．
已知复数z满足2-iZ=|3+4i|则Z=
设a=20.5b=0.52c=log20.5则abc的大小关系为
阅读下面短文根据其内容写一篇60词左右的内容概要.Parentseverywherepraisetheirkids.JennBermanauthorofTheAtoZGuidetoRaisingHappyandConfidentKidssays'We'vegonetotheoppositeextremeofafewdecadesagowhenparentstendedtobemorestrict.'Bygivingkidsalotofpraiseparentsthinkthey'rebuildingtheirchildren'sconfidencewheninfactitmaybejusttheopposite.Toomuchpraisecanbackfireandwhengiveninawaythat'sinsinceremakekidsafraidtotrynewthingsortakeariskforfearofnotbeingabletostayontopwheretheirparents'praisehasputthem.Stilldon'tgotoofarintheotherdirection.Notgivingenoughpraisecanbejustasdamagingasgivingtoomuch.Kidswillfeellikethey'renotgoodenoughorthatyoudon'tcareandasaresultmayseenopointintryinghardfortheiraccomplishments.Sowhatistherightamountofpraise?Expertssaythatthequalityofpraiseismoreimportantthanthequantity.Ifpraiseissincereandfocusedontheeffortnottheoutcomeyoucangiveitasoftenasyourchilddoessomethingthatdeservesaverbalreward.'Weshouldespeciallyrecognizeourchildren'seffortstopushthemselvesandworkhardtoachieveagoal'saysDonahueauthorofParentingWithoutFearLettingGoofWorryandFocusingonWhatReallyMatters.'Onethingtorememberisthatit'stheprocessnottheendproductthatmatters.'Yoursonmaynotbethebestbasketballplayeronhisteam.Butifhe'soutthereeverydayandplayinghardyoushouldpraisehiseffortregardlessofwhetherhisteamwinsorloses.Praisingtheeffortandnottheoutcomecanalsomeanrecognizingyourchildwhenshehasworkedhardtocleantheyardcookdinnerorfinishabookreport.Butwhateveritispraiseshouldbegivenonacase﹣by﹣casebasisandbeproportionate相称的totheamountofeffortyourchildhasputintoit.
若变量xy满足约束条件则z=3x﹣y的最大值是．
已知fx=|x﹣a|x+|x﹣2|x﹣a． 1当a=1时求不等式fx＜0的解集 2当x∈﹣∞1时fx＜0求a的取值范围．
We'veallhadcaseswherewe'vewaitedjustabittoolongtopayanelectricbillorspeedingticket.ButonemanfromCaliforniabyreasonableassumptionwhogoesbyDaverecentlytookprocrastination拖延onestepfurtherbypayingaparkingticketalmostahalf﹣centuryafteritwasgiven. InDecember2018theMinersvillePoliceDepartmentinPennsylvaniareceivedaletterinthemail.WhoeverwrotetheletterdecideditwasbesttokeephisnamesomewhatunknownsoheputthereturnaddressasWaywardRoadAnytownCaliforniaunderthenameFeelingguilty. Whentheofficersopenedtheenvelopetheyfoundabriefletteralongwitha＄5billandaparkingticketdatingallthewaybackto1974.ThenotereadDearPDI'vebeencarryingthisticketaroundfor40plusyearsalwaysintendingtopay.ForgivemeifIdon'tgiveyoumyinfo.WithrespectDave. Eventhoughtheinitialparkingticketwasonlyfor＄2Davemusthavefeltawfullyguiltybecauseheleft150percentor＄3ininterest. MichaelCombsthePoliceChiefoftheMinersvillePoliceDepartmentstatedinaninterviewthatthesameticketwouldcostabout＄20ifitwasgiventoday.Combswentontosharethattheoriginalticketfrom1974wasgiventoavehiclethathadanOhiolicenseplate. Becausetherewasnosystemfortrackingticketsgiventoout﹣of﹣statecarsbackthenDavecouldhavegottenawaywithneverpayingthe＄2fine.Butapparentlyguiltgotthebestofhimandhedecidedtofinallycoughupthemoneymorethan40yearspastitsduedate. 1HowmuchdoweknowaboutDave? A.HelivesinWaywardRoadAnytownCalifornia. B.Thepolicearetryingtofindoutmoreabouthim. C.HiscarprobablycamefromOhioatthattime. D.Daveisofcoursetheman'srealnameindeed. 2Whydidn'tDavepayfortheparkingticketuntilrecently? A.Hecompletelyforgotaboutitinthepast44years. B.Hedidn'tfindituntilalmosthalfacenturylater. C.Hefailedtofindoutwhoheshouldpaythemoneyto. D.Hedidn'tpayforitjustbecauseofprocrastination. 3WhatdroveDavetopayfortheparkingticketatlast? A.Astrongsenseofguilty. B.Fearofbeingtrackedbythepolice. C.Worryaboutbeingfinedmore. D.Suddenchangeofhisfinancialsituation. 4Whichofthefollowingcanbethebesttitle? A.PoliceChiefoftheMinersvillePoliceDepartmentSharesaStory B.MysteriousProcrastinatorFinallyPays44﹣Year﹣OldParkingTicket C.UnusualLetterComesfromWaywardRoadAnytownCalifornia D.ParkingTicketCarriedAroundforAlmostHalfaCenturyfromOhio
若抛物线y2=2pxp＞0的焦点是椭圆+=1的一个焦点则p=
ChinaisknownastheKingdomofBamboo.Morethan400speciesofbambooonethirdofallknownspeciesintheworldgrowinChina.China1leadtheworldintheamountofareaplantedwithbamboothenumberofbambootreesandtheamountofbamboowood2produceeveryyear. Theoldestbamboo3articleinChinawereunearthedfromtheremainsofaprimitivesocietythatexistedsome7000yearsagoin4isnowHemuduYuyaoCountyZhejiangProvince.AsearlyastheShangDynastyChinesepeopleusedthebambooformakingweaponssuchasbowsandarrows.Beforepaper5inventstripsofbamboowerethemostimportantwritingmediummorewidelyusedthansilk6theywerecheaperresistanttocorrosion腐蚀andmoreabundant.BamboohasthusplayedanimportantpartinthespreadanddevelopmentoftraditionalChineseculture. Bamboowas7closeconnectedwiththedailylivesofpeopleinancientChina.SuDongpoaliterarygiantoftheSongDynastysaidthatpeoplecouldnotlive8bamboo andpeopleofthetimeusedbamboo9makepaperhatsshoesandsoon.Atthattimeastodaybambooshootswereeatenasapopulardishbecauseof10theycrispnessandfreshsweettaste.Bambooshootsalsocontainvitaminssugarfatandprotein.
Hereallydidlooklikeatouristwithacameraaroundhisneckandabottleofsunscreenstickingoutofhisbag. Thefatmansatontheterrace草坪drinkinglemonadealittlebiteachtimeand1tolookatasmoothandshinycruisebrochure.Hissunglasses2hiseyesbutIknewhewasn'tlookingatthebrochurehehadn'tturneda3forthelasttenminutes. AsIbroughthimwhathehadorderedhecoughedupathankyouandlookedatme4.Itriednottostareatthetinyscaracrosshislefteyebrow. Iwalkedbackinsidewithmy5tray托盘shakingmyhead.Helooked6butIcouldn'tquiteplacehim. Thenit7me.Thecaraccident.The8strangerwhohelpedmeoutofmysmashedcar9beforeitexploded.I10backtohistable. Hewasgone. Imovedhissaucerandfoundhistipalongwitha11 Iamdeeply12toyou.ThenightofyourcaraccidentIwasonmywayto13ajewelrystore.Savingyour14broughtthingsbackinperspective看法.Inowliveanhonestlifethankstoyou.Godblessyou!Mr.D. Itrembled.ThenightofmycaraccidentIwas15foraninterviewinashadydanceclub.Seeinghumankindnessthroughhis16gestureturnedmylifearoundandbrought17backintomylife. I18thetipheleft.Amongtheone﹣dollarnoteswasa100﹣dollarnotewithapenmark19InGodWeTrustwhichfirstappearedonpapermoneyin1957. Isaidasilent20forhimandgotbacktoworksmiling. 1A.asking B.pretending C.refusing D.burning 2A.masked B.protected C.beautified D.comforted 3A.picture B.bottle C.page D.dish 4A.shyly B.worriedly C.fixedly D.briefly 5A.empty B.clean C.heavy D.new 6A.kind B.familiar C.sad D.puzzled 7A.attracted B.failed C.moved D.hit 8A.funny B.wealthy C.mysterious D.hungry 9A.even B.perhaps C.just D.long 10A.rushed B.inched C.struggled D.danced 11A.book B.card C.notice D.Poster 12A.committed B.attached C.guilty D.grateful 13A.rob B.visit C.help D.manage 14A.money B.face C.life D.Time 15A.waiting B.longing C.heading D.Preparing 16A.friendly B.heroic C.traditional D.Exciting 17A.happiness B.glory C.honesty D.faith 18A.dropped B.doubted C.weighed D.unfolded 19A.colouring B.underlining C.enlarging D.deleting 20A.prayer B.hello C.congratulation D.apology
Rockmusicconsistsofmanydifferentstyles.Eventhoughthereisacommonspiritamongallmusicgroupstheymakeverydifferentmusic.1AtthattimetheBeatlesenteredtheworldofmusicfromLiverpool. AftertheyweregivenaninvitationtoappearliveonBBCtheBeatlesquicklybecamefamousinBritainwithnationwidetours.Bymid﹣1963theBeatleshadbeenextremelypopularinEngland.2Theyheldlargeconcertsandperformedatclubs.TheybecamethehottestthingonthepopmusicsceneinEngland.Theybeganasamodestlysuccessfulmusiciangroupandendedtheyearasshowbusinesslegends传说.JohnLennonandPaulMcCartneywerenamedcomposersoftheyear. 3TheywerenotsurehowtheAmericanswouldreacttothenewtypeofmusic.BeatlemaniahitNewYorkonFebruary71964.Hundredsoffansjammedtheairporttogreetthem.4Theconcertwasbroadcastliveandattractedthelargestonenightaudienceinthehistoryoftelevisionuptothattime.TheBeatlesweredescribedasaBritishinvasion入侵bylocalandnationwidenewspapersatthattime.TheirvictoryinAmericawasstillrememberedasamajorturningpointinthehistoryofrockandroll.ThankstotheBeatlesalotofopportunitieswereopeneduptonewfacesonthemarket.5 A.TheydecidedonatourtotheUnitedStatesin1964. B.Eventheirhairstylesbecamemajortrendsatthattime. C.Rockmusicdevelopedinthe1950sandtheearly1960s. D.Howevertheirsongschangedthelivesofgenerationstocome. E.ManyrockbandswereabletofollowinthefootstepsoftheBeatles. F.TheyappearedinthefilmsAHardDay'sNight1964andHelp！1965. G.TheyperformedtheirfirstconcertinAmericaatCBStelevision's53rdstreetstudio.
LearntoManageYourTimeinCollege Acommonviewbothamongandofcollegestudentsisthattheyarealwaysshortonmoney.Whilethismaybetruemanycollegestudentsarealsoalwaysrunningshortonsomethingelsetime.1Hereareafewthingstoconsider Manageyouracademictime.2Consequentlyyouracademicworkshouldalwayscomefirstwhenitcomestoarrangingyourtimeinorderofimportance.Whenlookingatyourschedulefortheweekfigureoutwhatyouracademiccommitmentslooklike.Whattimedoyouhaveclasses?Howmuchhomeworkdoyouhavetodo?Whatassignmentsaredue?Whendoyouhavemajorexamsorquizzes? Manageyourpersonaltime.Itsanunrealisticexpectationtothinkthatyoucanstudygotoclassandworkalldayeveryday.3Makesuretoallowyourselftimetogotosomethingfunintheyardattendameetingforyourfavoriteclubandjusthangoutforanhourorsoatnightwithfriendsoverdinner.Doingthingsthatmakeyourpersonaltimemoreenjoyableandnottotallyfocusedonschool?canactuallyimproveyourproductivitywhenworkingonprojectslater. Keepyourhealthinmind.Whenpeople'sschedulesaretightoneofthefirstthingstogoissleep.Whileitmaybecommonamongcollegestudentsalackofsleepismorehurtfulthanyoumightthink.Itcanthroweverythingintodisorderyourmentalhealthyourphysicalhealthyourstresslevelandofcourseyourschedule.4 Useyourtechnology.Nothinghelpsacollegestudentstayorganizedmorethanagoodcalendar!SomestudentsusethecalendarsontheirphonesothersusethingslikeGoogleCalendarothersstillusetheclassicpaper﹣calendarmodel.5Justchangeandtryagain. A.Tryyourbesttokeeparoutineonaregularbasis. B.Rememberthatyourbrainneedstohaveabreaktoo. C.Ifwhatyou'reusingisn'tworkingforyoudon'tgiveup. D.Howcanyoubalanceyourtimewhenthereneverseemstobeenoughofit? E.It'simportanttorememberwhyyou'reincollegeinthefirstplacetograduate. F.Makingalistandthencrossingitemsoffastheyarecompletedcanbesatisfying. G.Takemomentstoplanoutthetimeforaweekyourhomeworksocialtimeandsleep.
已知双曲线-=1a＞0b＞0的左右焦点为F1F2过左焦点F1作垂直于x轴的直线交双曲线的两条渐近线于MN两点若∠MF2N是直角则双曲线的离心率是
假定英语课上老师要求同桌之间交换修改作文请你修改你同桌写的以下作文.文中共有10处语言错误每句中最多有两处.错误仅涉及一个单词的增加删除或修改.增加在缺词处加一个漏字符号∧并在其下面写出该加的词.删除把多余的词用\划掉.修改在错的词下画一横线并在该词下面写出修改后的词. 注意1.每处错误及其修改均仅限一词 2.只允许修改10处多者从第11处起不计分. Iusedtothinkcooperatingwasteoftimebutonethingchangesmymind.Onedaythescientificteacheraskedustodosomeresearchesandhandedintheconclusion.ThattookmelotsoftimetodotheresearchbutIstillcouldn'tfinishedit.SoItriedtocooperatewithothers.Wesharedourresearchesandthenmadethecompletelyconclusionsoon. SoIthinkcooperatingnotonlysavesourtimesbutalsohelpsustopromotethecommunicationwithothers.Althoughintheworldtodayveryfewthingscanbesuccessfullydonebyjustonepersoncooperatingcanbenefitfrombothorallsides.
TheAmericanHeartAssociationAHAsaysthattoomanypeoplearespendingfartoomuchtimeonchairsandcouches.BasedonexistingevidencewefoundthatU.S.adultsaresedentaryforaboutsixtoeighthoursadaysaidDeborahRohmYoungchairofAHApanelthatwrotethenewadvisory. AccordingtotheAHAgrowingevidenceshowsthatonitsownexerciseisn'tenoughtocancelouttheunhealthyeffectsofsittingforalongtime.RegardlessofhowmuchphysicalactivitysomeonegetslongsedentarytimecouldnegativelyinfluencethehealthofyourheartandbloodvesselsYoungexplained. Theexactmechanismsbehindtheeffectaren'tyetclear.Therearemanyimportantfactorswedon'tunderstandaboutsedentarytimeyetYoungsaid.Shestressedthatthetypesofstudiesavailableidentifytrendsbutdon'tprovecauseandeffect. Wedon'thaveinformationabouthowmuchsedentarybehaviorisbadforhealth﹣thebestadviceatthistimeisto‘sitlessandmovemoresheadded. Howmuchmore?AccordingtotheAHApeopleshouldtrytogetatleast30minutesofmoderatetovigorous剧烈的exerciseadaytoreachtherecommended150minutesofmoderateexerciseor75minutesofvigorousexerciseaweekThat'shealthierthantryingtocramtheirweeklyexerciseintooneortwodaysaccordingtothestatement. TherealrisksimplycomesdowntotheamountwesitwithouttherebeingatruemedicineormethodtocontroltheharmfuleffectssaidSteinbaumapreventivespecialistinheartdisease. Stillsocietyhasevolvedtoencouragesittingsheadded. Ourliveshavebecomefocusedaroundactivitiesrequiringustobestill﹣whetheritbetransportationourcomputersorthetelevisionorcomputerinourleisuretimeSteinbaumsaid.Sociologicallyinsteadofbeingactivetobeproductiveortohaveenjoymentourproductivityandfunoftenrequiresminimalphysicalactivities. 1WhatisthemainpurposeofthenewadvisorydeliveredbyAHA? A.Toadvisepeopletositlessandexercisemore. B.Toexplorethecauseandeffectofinactivebehavior. C.Toanalyzethelinkbetweenhearthealthandexercise. D.Toshowthegeneralsocialtrendofencouragingsilting. 2WhichofthefollowingwouldDeborahRohmYoungmostprobablyagreewith? A.Doingexerciseisofnobenefittothosecouchpotatoes. B.Sittingtoomuchisacontributingfactortoheartdiseases. C.Theexactcausebehindtheeffectoflong﹣timesittingisapparent. D.Thevitalthingforhealthisthetotalamountofweeklyexerciseyoudo. 3AccordingtoSteinbaumtheincreaseofsittingtimeis. A.abasicaspectofpromotingthequalityoflife B.arealriskthatcanberemovedbyvigorousexercise C.anunavoidableconsequenceofsocialdevelopment D.abigchangeinmodempeople'sconceptofhealth
Thereareseveralreasonswhyschooluniformsaregoodidea.Firstofalluniformshelptheschoollooksmart.Thestudentsfeelthattheybelongtoaparticulargroup.Wheneverypupilintheschoolwearstheuniformnobody1havetoworryaboutfashion时尚.Everybodywears2samestyleofclothes.Uniformscanbeusefulinunexpectedways.AschoolinIrelandhasintroducedaninterestingnewuniform.Ontheedgeofthejacketthereisapieceofcloth3givesofflightinthedark.Whenthechildrenarewalkingor4cycletoschoolondarkmorningscardriverscan5easyseethem. Butcanuniformshelpimproveschoolstandards?Theanswer6thisquestionisnotclear.OnestudyinAmericafoundthatstudents'grades7improvealittleaftertheschoolintroduceduniforms.Butsomestudentsdidn'twant8weartheuniform.OtherAmericanstudiesshowedno9connectbetweenuniformsandschoolperformance. Schooluniformsare10traditioninBritainbutsomeschoolsarestartingtogetridofthem.Someverygoodschoolsdon'thaveauniformpolicy.Howeveruniformsarestillpopular.Pupilsatabout90percentofBritishsecondaryschoolswearuniforms.
已知关于x的方程ex-2x-k=0有2个不相等的实数根则k的取值范围是
已知α∈02sin2α=cos2α+1则sinα=
Moneywithnostringsattached.It'snotsomethingyouseeeveryday.ButatUnionStationinLosAngeleslastmonthaboardwentupwithdollarbillsattachedtoitwithpinsandasignthatreadGiveWhatYouCanTakeWhatYouNeed. Peoplequicklycaughton.Andwhilemanytookdollarsmanyotherspinnedtheirowncashtotheboard.Peopleofallagesracesandsocio﹣economic社会经济的backgroundsgaveandtooksaidTylerBridgesofTheToolboxwhichcreatedtheproject.Weevenhadabrideinherweddingdresscomeuptotheboardandtakeafewdollars.Mostofthebillsontheboardweresinglesbutafewpeopleleftfivestensandeventwenties.Thevideoclip片段showsonemanwhohadfounda$20billpinningittotheboard. WhatIcansayforthefolksthatgavethemostisthattheywerefullofsmilesBridgessaid.There'sacertainfeelingthatgivingcandoforyouandthatwasapparentinthosethatgavethemost.MostpeoplewhotookdollarstookonlyafewbutBridgessaidaverysmallnumbertookasmuchastheycould. WhiletheclipmightlooklikepartofanewadcampaignBridgessaidtheonlygoalwastoshowgenerosityandsympathy.HeaddedthathehopespeopleinothercitiesmighttrysimilarprojectsandposttheirownvideosontheInternet. Afteralleveryonehasbaddaysandgooddayshesaid.Somedaysyouneedahelpinghandandsomedaysyoucanbetheonegivingthehelpinghand. 1Whatdoestheexpressionmoneywithnostringsattachedinparagraph1mean? A.Moneyspentwithouthesitation. B.Moneynotlegallymade. C.Moneyofferedwithoutconditions. D.Moneynottiedtogether. 2WhatdidBridgeswanttoshowbymentioningthebride? A.Womentendedtobemoresociable. B.Theactivityattractedvariouspeople. C.Economicproblemsweregettingworse. D.Youngcouplesneededfinancialassistance. 3WhydidBridgescarryouttheproject? A.Todoatestonpeople'smorals. B.Toraisemoneyforhiscompany. C.Toearnhimselfagoodreputation. D.Topromotekindnessandsympathy.
已知向量=23=32则|﹣|=
在“一带一路”知识测验后甲乙丙三人对成绩进行预测． 甲我的成绩比乙高． 乙丙的成绩比我和甲的都高． 丙我的成绩比乙高． 成绩公布后三人成绩互不相同且只有一个人预测正确那么三人按成绩由高到低的次序为
△ABC的内角ABC的对边分别为abc．已知bsinA+acosB=0则B=．
已知函数fx=x﹣1lnx﹣x﹣1．证明 1fx存在唯一的极值点 2fx=0有且仅有两个实根且两个实根互为倒数．
设αβ为两个平面则α∥β的充要条件是
热门题库
更多
高三下学期数学
高三上学期数学
高一下学期英语
教案备课库
高一上学期生物
高一下学期生物
高二上学期数学
高二上学期物理
高二上学期英语
高二上学期生物
高二下学期数学
高二上学期化学
高二下学期物理
高三下学期物理
高三上学期物理
高三上学期生物
，1） （1，） （1,2）
湘公网安备 43130202000226号