高考英语一轮总复习练案14必修3Unit4Astronomy：thescienceofthestars练习含解析新人教版

一轮复习精品资料(高中)PAGEPAGE1必修三Unit4Astronomy：thescienceofthestarsⅠ.完形填空(2020·甘肃省重点中学协作体第一次联考)Fromanearlyage,Parkeralwayssaidthathewouldbeanastronautwhenhegrewup.Butnomatterhowmuchhestudiedandtooktests,hewasnever1.Btoflyinspace.2.D，hegrewoverthemaximumagefortakingtheselectiontests.Inotherwords,hewouldneverbeabletofulfillhis3.A.Thinkingaboutallthetimeand4.CParkerhadputintotryingtobeanastronaut,peoplefelt5.Bforhim.Despitewhathewastoldabouthavingto6.Dhisambition,Parkercontinuedtrainingandstudying,7.Chewasgoingtohavetheteststhenextmonth.He8.Aashegotolder,andwhenhewasaveryoldmanheheardthattheyweredoingsomeveryimportant9.Cexperiments.Forthoseexperimentstheyneededavery10.Dastronaut.Parker,whowalkedwitha11.B，wastheonlyoldmaninthewholeworldwhowas12.Btoflyinarocket.Therefore,Parkerfoundhimselfflyingin13.D，allwiththehelpofscience.Itwasclearthatthe14.Againedduringthosemissionshelpedtocureoneoftheworstsicknessesforoldpeople,andParkerwas15.Casahero.Photosoftheastronautwithawalkingstickandnoteeth16.Callovertheworld,andbecamea17.Aofhowyoucannevertrainorlearntoomuch.Itshowedthat18.Beffortalwaysbrings19.Deventhoughitmaynotbeintheformwehadfirst20.A.文章大意：Parker从小立志做一名宇航员，却一直未实现自己的梦想。但他从未放弃希望，一如既往地进行飞行训练。终于在年老时实现了自己的愿望。1．A.noticed B．selectedC．invited D．permitted〖解析〗根据下文中的“hegrewoverthemaximumagefortakingtheselectiontests”可知，此处指他从来没有被选(selected)去太空飞行。2．A.Secretly B．SuddenlyC．Luckily D．Finally〖解析〗最后，Parker已经超过了选拔考试的最大年龄。finally“最终；终于”。3．A.dream B．taskC．need D．belief〖解析〗文章开头谈及Parker的梦想，因为他已经超过了选拔考试的最大年龄，所以他永远也无法实现他的梦想(dream)。4．A.reputation B．powerC．effort D．practice〖解析〗根据第一段中的“Butnomatterhowmuchhestudiedandtooktests”可知，Parker付出了很多时间和努力(effort)。人们一想到Parker为成为宇航员所付出的时间和努力就为他感到遗憾(sorry)。5．A.happy B．sorryC．nervous D．calm〖解析〗参见上题〖解析〗。6．A.ignore B．forgetC．develop D．abandon〖解析〗尽管有人告诉Parker，他不得不放弃(abandon)他的目标，但他还是继续训练和学习，好像(asif)下个月他要参加测试似的。7．A.sothat B．nowthatC．asif D．eventhough〖解析〗参见上题〖解析〗。8．A.carriedon B．tookonC．turnedoff D．gotoff〖解析〗Parker继续(学习和训练)。carryon“继续做；坚持干”，符合语境。9．A.electrical B．physicalC．medical D．political〖解析〗根据下文中的“duringthosemissionshelpedtocureoneoftheworstsicknessesforoldpeople”可知，Parker得知他们在太空做医学实验。medical“医疗的”，符合语境。electrical“用电的”；physical“物理学的”；political“政治的”。10．A.sick B．experiencedC．active D．old〖解析〗根据语境可知，他们需要一位年纪大的(old)宇航员。11．A.map B．stickC．guide D．candle〖解析〗根据下文中的“Photosoftheastronautwithawalkingstick”可知，当时Parker走路需要拐杖。awalkingstick“拐杖”。12．A.planned B．trainedC．forced D．allowed〖解析〗根据上文内容可知，Parker参加训练就是为了能够在太空飞行。故B项符合语境。13．A.silence B．dangerC．action D．space〖解析〗根据语境可知，此处指Parker参加实验后，发现自己在太空(space)飞行。14．A.knowledge B．experienceC．money D．opportunity〖解析〗在那些任务中所获得的知识(knowledge)有助于治愈老人们最严重的疾病之一。15．A.replaced B．educatedC．praised D．affected〖解析〗Parker被人们称赞(praised)为一位英雄。replace“代替”；educate“教育”；affect“影响”。16．A.moved B．flewC．spread D．took〖解析〗这位拄着拐杖且没有牙齿的宇航员的照片在全世界传播(spread)开来。17．A.symbol B．markC．case D．doubt〖解析〗Parker的照片成了一种象征(symbol)——你再怎么去学习和训练都不为过。18．A.desperate B．persistentC．cautious D．apparent〖解析〗这表明坚持不懈的(persistent)努力总会带来回报(reward)。desperate“绝望的”；cautious“小心的”，apparent“显而易见的”。19．A.award B．prizeC．result D．reward〖解析〗参见上题〖解析〗。20．A.expected B．guessedC．suggested D．proved〖解析〗坚持不懈的努力总会带来回报，尽管它不是我们最初所期待(expected)的那种形式。Ⅱ.阅读理解(2020·“四省八校”高三第一次教学质检)(CNN)—YOUcouldsaythingsaregettingalittlemoreconcreteontheInternationalSpaceStation.Astronautsareworkingonhundredsofexperimentsonthefloatinglaboratoryeveryday.Onerecentexperimentincludedmixingconcreteforthefirsttime.Thebasicingredientsforconcreteincludesand,gravelandrocksmixedwithacementwaterbasedpaste.Itsoundsaseasyaswhippingupcakemix,buttheactualprocessismuchmoredifficult,andthelackofgravitychangeseverything.AstronautsparticipatedintheMicrogravityInvestigationofCementSolidificationprojecttounderstandhowthechemistryofconcreteischangedbyzerogravity,downtothemicroscopicstructuresinsideit.Avarietyofmixturesweremadewherecementpowder,additives,waterandtimeallowancevaried.ThespacestationmixtureswerecomparedtosamplesmixedonEarth.Theconcreteinspaceendedupbeingmoreholey,whichisinterestingbecausemoreholesinsidetheconcretewouldaffectitsstrength.“Increasedporosity(疏松)hasdirectinfluencesonthestrengthofthematerial,butwehaveyettomeasurethestrengthofthespace-formedmaterial，”，saidRadlinska,principalinvestigatoroftheexperiment.“EventhoughconcretehasbeenusedforsolongontheEarth,westilldon'tnecessarilyunderstandalltheaspectsofthehydration(水合作用)weknowtherearesomedifferencesbetweenEarthandspace-basedsystemsandwecanexaminethosedifferencestoseewhichonesarebeneficialandwhichonesareharmfultousingthismaterialinspace.”Radlinskaalsonotedthatthesamplesweremixedinsealedbagswhichleavesthequestionofwhatmighthappenhadtheybeenmixedinanopenenvironmentinspace.UnderstandinghowconcreteworksinspacehasadirectinfluenceonfutureplansregardingthemoonandMars.Buildingsafehabitatsmayrelyonconcretebecauseitcouldprotecthumansandtheequipmentfrommeteoritesandharmfulradiation.IngredientsalreadyavailableonMarsorthemooncouldalsobeusedtomaketheconcrete,whichwouldreducethecostoftransportingmaterials.文章大意：本文是一篇说明文。介绍了在太空做混凝土实验，实验结果表明太空中的混凝土与地球上的不同，并提出实验的意义在于为太空建筑选取材料。1．Whatistheaimoftheexperiment？BA．Tocheckwhetherconcretecanbemadeinspace.B．Toseethedifferentformationofconcreteinspace.C．Totestthestrengthofconcretemadeinspace.D．Tobuildsheltersinspaceusingconcrete.〖解析〗细节理解题。根据第三段“tounderstandhowthechemistryofconcreteischangedbyzerogravity”可知，实验的目的是了解在失重状态下混凝土的化学变化。故选B。2．Whatdoweknowabouttheexperiment？CA．Itwasdoneintheopenenvironmentinspace.B．ItusedingredientsonMarsandthemoon.C．Itmademultiplemixturesunderdifferentconditions.D．ItexaminedthedifferenceofstrengthbetweenconcreteonEarthandinspace.〖解析〗细节理解题。根据第四段第一句话“Avarietyofmixturesweremadewherecementpowder,additives,waterandtimeallowancevaried.”可知，实验中根据水泥粉、添加剂、水和时间的不同制造了多种混凝土。故选C。3．ComparedwithconcretemadeonEarth,concretemadeinspaceA.A．hasmoreopenspaceinsideitB．ismuchmorefragileC．canbeusedonMarsandthemoonatthemomentD．isnotasgoodineveryaspect〖解析〗细节理解题。根据第四段第三句话“Theconcreteinspaceendedupbeingmoreholey,whichisinterestingbecausemoreholesinsidetheconcretewouldaffectitsstrength.”可知，太空中制造的混凝土里面有更多孔。故选A。4．Whattypeofpassageisthis？BA．Bookreview. B．Newsreport.C．Sciencefiction. D．Traveljournal.〖解析〗文章出处题。根据第一段开头CNN可知，这是一篇新闻报道。故选B。Ⅲ.阅读七选五Gardening380KilometersaboveEarthAstronautshavetogothroughphysical,psychological,andtechnicaltraining.Theyalsogothroughtraininginhowtocareforplants.These“astronautgardeners”sharetheirworkandlivingspacewithplants.Takingseedsandplantsalongonatripisn'tanewidea.Asspacetripsbecomelonger,itwillbenecessarytogrowfoodinspace.1.DBecauseofthis,it'snotpracticaltosendeverythingneededforalongjourney,onlytobeusedonceandthrownaway.Plantscanservemanyusesonaspacejourney.Theycanprovidemorefreshthings.2.FAlso,plantscanhelptomakeairqualitybetterbecausetheyproduceoxygen.Theycanimprovethequalityoftheairinsidethespacecraft—theonlyairtheastronautscanbreathe.3.BDuetothelackofgravityinspace,theoxygenthattheplantsproducestaysaroundtheplants.Thiscanactuallykillthem,sofansareneededtocirculatetheair.Withoutgravity,rootsdon't“know”togrowdown,leavesdon't“know”togrowup,andwaterdoesn'teasilytraveluptherootstotheleaves.4.EBesides,soilistooheavytosendtospace,andspecialliquidgels(凝胶)areusedtohelpplantgrowth.Scientistsarealsoworkingontheplantsthemselves.Theyaretryingtomakeplantsgrowmorerapidlyandgrowwithlesswaterandlightinspace,andtheyarelookingforwaystomakeplantsmoreresistanttodisease.5.CImaginethatdesertsmayonedayprovidelotsoffreshfoodforlocalpeople,savingtransportationcosts.Similarly,plantsthatareresistanttodiseasecouldprovideanimportantfoodsupply.Withtheworld'spopulationnowatabout7.7billionpeople,ourastronautgardenersmayhelpdiscoverwaystofeedthosebillions.A．Everyplantgrowninspacemusthaveseveraluses.B．However,therearechallengeswithgrowingplantsinspace.C．SuchmethodsmayresultinimprovementsbackhereonEarth.D．Thecostoftakinganythingintospaceisabout$22,000perkilogram.E．Specializedcontainersarebeingdevelopedtohelptheplantsgrowcorrectly.F．Astronautswillwelcometheadditionoffruitsandvegetablestotheirdietofdryfoods.G．Currentlyalloxygenistakenaboardintanks.文章大意：本文是一篇说明文。主要介绍了宇航员在太空种植的原因和好处以及种植方法。〖解析〗1．空后是说将所有所需东西带上太空是不切合实际的，据此可推知，空处应是介绍空后一句的原因，故D项“带任何东西到太空的花费大约是每千克22000美元。”符合语境。2．根据空前一句可知，植物可以为宇航员提供新鲜的东西，根据空后一句可知，植物还可以改善太空站的空气质量，因为其可以产生氧气，据此可推知，空处应是介绍太空种植植物的好处，即宇航员也喜欢在他们的干粮中有新鲜的果蔬食物。故F项正确。3．上文介绍了太空种植的好处，即为宇航员提供新鲜的果蔬、改善太空站的空气质量等，结合下文可知，种植太空果蔬有一定的困难，据此可知，空处承上启下，与上文形成转折关系。故B项正确。4．根据上文可知，在失重的情况下，植物的根和叶不知道如何生长，水分也不容易从根部传到叶子上，而空后一句介绍了关于土壤的解决方法，据此可推知，空处应是介绍解决上述问题的方法，故E项“正在研制专门的容器去帮助植物正确地生长。”符合语境。5．根据空前一句可知，科学家们正在寻找各种让植物少使用水，在太空快速生长，而且可以抵抗病害的方法，且下文又提到改良后的植物对地球的影响，据此可推知，空处应是说明这些方法可以在地球上运用以带来改善。故C项正确。Ⅳ.语法填空(2020·武汉市高中毕业生六月)Hereiswhyyoushouldcareaboutastronomy.It'struethatitsadvancesbenefitmillionsofpeopleacrosstheworld.Ithasdevelopedtechnologynowtotrackwhereyourpackagegoes,todeterminewhereyouareandso1.on.Butallofthesearemeresecondthoughtsand2.benefits(benefit)thathaveoccurredwithouttheprimary3.intention(intend)ofthemaker.Andthatis4.whatmakesastronomybeautiful.Tostudysomething—notbecausewe'relookingtogainanythinginparticular,butpurely5.toenjoy(enjoy)naturalwonders—6.is(be)allthatmakesushuman.Doingworkfortheworkitselfcreatesroomforjoy.I7.firmly(firm)believethatastronomyhasaspiritualdimensioninthesenseofhowitconnectsuswithsomethingbiggerthanourselves.Because8.ofastronomywenowknowexactlywhentheuniverse9.came(come)intoexistence.Andwe'vespottedthousandsofplanetsorbitingotherstars.Ithasexplainedmysteries(神秘的事物)10.confusing(confuse)usforthousandsofyears,butevenmoresignificantly,ithasopenedupmoremysteriesthananyofuscanstudyinourlifetime.文章大意：本文是一篇说明文。主要介绍了我们应该关注天文学的原因。〖解析〗1．考查固定搭配。andsoon为固定搭配，意为“等等”，符合语境。2．考查名词的单复数。分析该句结构可知，该句中that引导定语从句，空处与thoughts为先行词，空处与复数名词thoughts对应，benefit为可数名词，故该处用其复数形式benefits。3．考查名词。根据空前的“withouttheprimary”可知，空处应用名词的单数形式，故填intend的名词单数形式intention。4．考查表语从句连接词。分析该句结构可知，空处引导表语从句，作表语从句的主语，表示“……的事物”，故用what引导该表语从句。5．考查动词不定式。空处与togain并列，表示目的，故用动词不定式作目的状语。6．考查主谓一致和动词的时态。该句主语为不定式“Tostudysomething”，故谓语动词应用单数形式；又根据语境可知，该句陈述的是客观存在的情况，故用一般现在时。7．考查副词。空处修饰动词believe，应用副词形式，表示“坚定地相信”。8．考查介词。becauseof为固定搭配，意为“因为，由于”，符合语境，故填介词of。9．考查动词的时态。根据语境可知，该句意为“由于天文学，我们现在确切地知道宇宙是什么时候形成的”。根据常识可知，宇宙的形成是发生在过去的事情，故用一般过去时。10．考查现在分词。分析该句结构可知，空处修饰前面的名词mysteries，该名词和动词confuse之间为逻辑上的主谓关系，故用现在分词作后置定语。必修三Unit4Astronomy：thescienceofthestarsⅠ.完形填空(2020·甘肃省重点中学协作体第一次联考)Fromanearlyage,Parkeralwayssaidthathewouldbeanastronautwhenhegrewup.Butnomatterhowmuchhestudiedandtooktests,hewasnever1.Btoflyinspace.2.D，hegrewoverthemaximumagefortakingtheselectiontests.Inotherwords,hewouldneverbeabletofulfillhis3.A.Thinkingaboutallthetimeand4.CParkerhadputintotryingtobeanastronaut,peoplefelt5.Bforhim.Despitewhathewastoldabouthavingto6.Dhisambition,Parkercontinuedtrainingandstudying,7.Chewasgoingtohavetheteststhenextmonth.He8.Aashegotolder,andwhenhewasaveryoldmanheheardthattheyweredoingsomeveryimportant9.Cexperiments.Forthoseexperimentstheyneededavery10.Dastronaut.Parker,whowalkedwitha11.B，wastheonlyoldmaninthewholeworldwhowas12.Btoflyinarocket.Therefore,Parkerfoundhimselfflyingin13.D，allwiththehelpofscience.Itwasclearthatthe14.Againedduringthosemissionshelpedtocureoneoftheworstsicknessesforoldpeople,andParkerwas15.Casahero.Photosoftheastronautwithawalkingstickandnoteeth16.Callovertheworld,andbecamea17.Aofhowyoucannevertrainorlearntoomuch.Itshowedthat18.Beffortalwaysbrings19.Deventhoughitmaynotbeintheformwehadfirst20.A.文章大意：Parker从小立志做一名宇航员，却一直未实现自己的梦想。但他从未放弃希望，一如既往地进行飞行训练。终于在年老时实现了自己的愿望。1．A.noticed B．selectedC．invited D．permitted〖解析〗根据下文中的“hegrewoverthemaximumagefortakingtheselectiontests”可知，此处指他从来没有被选(selected)去太空飞行。2．A.Secretly B．SuddenlyC．Luckily D．Finally〖解析〗最后，Parker已经超过了选拔考试的最大年龄。finally“最终；终于”。3．A.dream B．taskC．need D．belief〖解析〗文章开头谈及Parker的梦想，因为他已经超过了选拔考试的最大年龄，所以他永远也无法实现他的梦想(dream)。4．A.reputation B．powerC．effort D．practice〖解析〗根据第一段中的“Butnomatterhowmuchhestudiedandtooktests”可知，Parker付出了很多时间和努力(effort)。人们一想到Parker为成为宇航员所付出的时间和努力就为他感到遗憾(sorry)。5．A.happy B．sorryC．nervous D．calm〖解析〗参见上题〖解析〗。6．A.ignore B．forgetC．develop D．abandon〖解析〗尽管有人告诉Parker，他不得不放弃(abandon)他的目标，但他还是继续训练和学习，好像(asif)下个月他要参加测试似的。7．A.sothat B．nowthatC．asif D．eventhough〖解析〗参见上题〖解析〗。8．A.carriedon B．tookonC．turnedoff D．gotoff〖解析〗Parker继续(学习和训练)。carryon“继续做；坚持干”，符合语境。9．A.electrical B．physicalC．medical D．political〖解析〗根据下文中的“duringthosemissionshelpedtocureoneoftheworstsicknessesforoldpeople”可知，Parker得知他们在太空做医学实验。medical“医疗的”，符合语境。electrical“用电的”；physical“物理学的”；political“政治的”。10．A.sick B．experiencedC．active D．old〖解析〗根据语境可知，他们需要一位年纪大的(old)宇航员。11．A.map B．stickC．guide D．candle〖解析〗根据下文中的“Photosoftheastronautwithawalkingstick”可知，当时Parker走路需要拐杖。awalkingstick“拐杖”。12．A.planned B．trainedC．forced D．allowed〖解析〗根据上文内容可知，Parker参加训练就是为了能够在太空飞行。故B项符合语境。13．A.silence B．dangerC．action D．space〖解析〗根据语境可知，此处指Parker参加实验后，发现自己在太空(space)飞行。14．A.knowledge B．experienceC．money D．opportunity〖解析〗在那些任务中所获得的知识(knowledge)有助于治愈老人们最严重的疾病之一。15．A.replaced B．educatedC．praised D．affected〖解析〗Parker被人们称赞(praised)为一位英雄。replace“代替”；educate“教育”；affect“影响”。16．A.moved B．flewC．spread D．took〖解析〗这位拄着拐杖且没有牙齿的宇航员的照片在全世界传播(spread)开来。17．A.symbol B．markC．case D．doubt〖解析〗Parker的照片成了一种象征(symbol)——你再怎么去学习和训练都不为过。18．A.desperate B．persistentC．cautious D．apparent〖解析〗这表明坚持不懈的(persistent)努力总会带来回报(reward)。desperate“绝望的”；cautious“小心的”，apparent“显而易见的”。19．A.award B．prizeC．result D．reward〖解析〗参见上题〖解析〗。20．A.expected B．guessedC．suggested D．proved〖解析〗坚持不懈的努力总会带来回报，尽管它不是我们最初所期待(expected)的那种形式。Ⅱ.阅读理解(2020·“四省八校”高三第一次教学质检)(CNN)—YOUcouldsaythingsaregettingalittlemoreconcreteontheInternationalSpaceStation.Astronautsareworkingonhundredsofexperimentsonthefloatinglaboratoryeveryday.Onerecentexperimentincludedmixingconcreteforthefirsttime.Thebasicingredientsforconcreteincludesand,gravelandrocksmixedwithacementwaterbasedpaste.Itsoundsaseasyaswhippingupcakemix,buttheactualprocessismuchmoredifficult,andthelackofgravitychangeseverything.AstronautsparticipatedintheMicrogravityInvestigationofCementSolidificationprojecttounderstandhowthechemistryofconcreteischangedbyzerogravity,downtothemicroscopicstructuresinsideit.Avarietyofmixturesweremadewherecementpowder,additives,waterandtimeallowancevaried.ThespacestationmixtureswerecomparedtosamplesmixedonEarth.Theconcreteinspaceendedupbeingmoreholey,whichisinterestingbecausemoreholesinsidetheconcretewouldaffectitsstrength.“Increasedporosity(疏松)hasdirectinfluencesonthestrengthofthematerial,butwehaveyettomeasurethestrengthofthespace-formedmaterial，”，saidRadlinska,principalinvestigatoroftheexperiment.“EventhoughconcretehasbeenusedforsolongontheEarth,westilldon'tnecessarilyunderstandalltheaspectsofthehydration(水合作用)weknowtherearesomedifferencesbetweenEarthandspace-basedsystemsandwecanexaminethosedifferencestoseewhichonesarebeneficialandwhichonesareharmfultousingthismaterialinspace.”Radlinskaalsonotedthatthesamplesweremixedinsealedbagswhichleavesthequestionofwhatmighthappenhadtheybeenmixedinanopenenvironmentinspace.UnderstandinghowconcreteworksinspacehasadirectinfluenceonfutureplansregardingthemoonandMars.Buildingsafehabitatsmayrelyonconcretebecauseitcouldprotecthumansandtheequipmentfrommeteoritesandharmfulradiation.IngredientsalreadyavailableonMarsorthemooncouldalsobeusedtomaketheconcrete,whichwouldreducethecostoftransportingmaterials.文章大意：本文是一篇说明文。介绍了在太空做混凝土实验，实验结果表明太空中的混凝土与地球上的不同，并提出实验的意义在于为太空建筑选取材料。1．Whatistheaimoftheexperiment？BA．Tocheckwhetherconcretecanbemadeinspace.B．Toseethedifferentformationofconcreteinspace.C．Totestthestrengthofconcretemadeinspace.D．Tobuildsheltersinspaceusingconcrete.〖解析〗细节理解题。根据第三段“tounderstandhowthechemistryofconcreteischangedbyzerogravity”可知，实验的目的是了解在失重状态下混凝土的化学变化。故选B。2．Whatdoweknowabouttheexperiment？CA．Itwasdoneintheopenenvironmentinspace.B．ItusedingredientsonMarsandthemoon.C．Itmademultiplemixturesunderdifferentconditions.D．ItexaminedthedifferenceofstrengthbetweenconcreteonEarthandinspace.〖解析〗细节理解题。根据第四段第一句话“Avarietyofmixturesweremadewherecementpowder,additives,waterandtimeallowancevaried.”可知，实验中根据水泥粉、添加剂、水和时间的不同制造了多种混凝土。故选C。3．ComparedwithconcretemadeonEarth,concretemadeinspaceA.A．hasmoreopenspaceinsideitB．ismuchmorefragileC．canbeusedonMarsandthemoonatthemomentD．isnotasgoodineveryaspect〖解析〗细节理解题。根据第四段第三句话“Theconcreteinspaceendedupbeingmoreholey,whichisinterestingbecausemoreholesinsidetheconcretewouldaffectitsstrength.”可知，太空中制造的混凝土里面有更多孔。故选A。4．Whattypeofpassageisthis？BA．Bookreview. B．Newsreport.C．Sciencefiction. D．Traveljournal.〖解析〗文章出处题。根据第一段开头CNN可知，这是一篇新闻报道。故选B。Ⅲ.阅读七选五Gardening380KilometersaboveEarthAstronautshavetogothroughphysical,psychological,andtechnicaltraining.Theyalsogothroughtraininginhowtocareforplants.These“astronautgardeners”sharetheirworkandlivingspacewithplants.Takingseedsandplantsalongonatripisn'tanewidea.Asspacetripsbecomelonger,itwillbenecessarytogrowfoodinspace.1.DBecauseofthis,it'snotpracticaltosendeverythingneededforalongjourney,onlytobeusedonceandthrownaway.Plantscanservemanyusesonaspacejourney.Theycanprovidemorefreshthings.2.FAlso,plantscanhelptomakeairqualitybetterbecausetheyproduceoxygen.Theycanimprovethequalityoftheairinsidethespacecraft—theonlyairtheastronautscanbreathe.3.BDuetothelackofgravityinspace,theoxygenthattheplantsproducestaysaroundtheplants.Thiscanactuallykillthem,sofansareneededtocirculatetheair.Withoutgravity,rootsdon't“know”togrowdown,leavesdon't“know”togrowup,andwaterdoesn'teasilytraveluptherootstotheleaves.4.EBesides,soilistooheavytosendtospace,andspecialliquidgels(凝胶)areusedtohelpplantgrowth.Scientistsarealsoworkingontheplantsthemselves.Theyaretryingtomakeplantsgrowmorerapidlyandgrowwithlesswaterandlightinspace,andtheyarelookingforwaystomakeplantsmoreresistanttodisease.5.CImaginethatdesertsmayonedayprovidelotsoffreshfoodforlocalpeople,savingtransportationcosts.Similarly,plantsthatareresistanttodiseasecouldprovideanimportantfoodsupply.Withtheworld'spopulationnowatabout7.7billionpeople,ourastronautgardenersmayhelpdiscoverwaystofeedthosebillions.A．Everyplantgrowninspacemusthaveseveraluses.B．However,therearechallengeswithgrowingplantsinspace.C．SuchmethodsmayresultinimprovementsbackhereonEarth.D．Thecostoftakinganythingintospaceisabout$22,000perkilogram.E．Specializedcontainersarebeingdevelopedtohelptheplantsgrowcorrectly.F．Astronautswillwelcometheadditionoffruitsandvegetablestotheirdietofdryfoods.G．Currentlyalloxygenistakenaboardintanks.文章大意：本文是一篇说明文。主要介绍了宇航员在太空种植的原因和