专题十六阅读理解之科普类说明文1.【2015·湖北卷】DTheoddnessoflifeinspaceneverquitegoesaway.Herearesomeexamples.Firstconsidersomethingassimpleassleep.Itspositionpresentsitsownchallenges.Themainquestioniswhetheryouwantyourarmsinsideoroutsidethesleepingbag.Ifyouleaveyourarmsout,theyfloatfreeinzerogravity,oftengivingasleepingastronautthelookofafunnyballed（芭蕾）dancer.“I’maninsideguy,”MikeHopkinssays,whoreturnedfromasix-monthtourontheInternationalSpaceStation.“Iliketobewrappedup.”Onthestation,theordinarybecomesstrange.TheexercisebikefortheAmericanastronautshasnohandlebars.Italsohasnoseat.Withnogravity,it’sjustaseasytopedalviolently.Youcanwatchamoviewhileyoupedalbyfloatingamicrocomputeranywhereyouwant.Butstationresidentshavetobecarefulaboutstayinginoneplacetoolong.Withoutgravitytohelpcirculateair,thecarbondioxideyouexhale(呼气)hasatendencytoformaninvisible（隐形的）cloudaroundyouhead.Youcanendupwithwhatastronautscallacarbon-dioxideheadache.LeroyChiao,54,anAmericanretiredastronautafterfourflights,describeswhathappensevenbeforeyoufloatoutofyourseat,”Yourinnerearthinksyour’refalling.Meanwhileyoureyesaretellingyouyou’restandingstraight.Thatcanbeannoying—that’swhysomepeoplefeelsick.”Withinacoupledays—trulyterribledaysforsome—astronauts’brainslearntoignorethepanickysignalsfromtheinnerear,andspacesicknessdisappears.Spacetravelcanbesodelightfulbutatthesametimeinvisiblydangerous.Forinstance,astronautslosebonemass.That’swhyexerciseisconsideredsovitalthatNationalAeronauticsandSpaceAdministration(NASA)putsitrightontheworkdayschedule.Thefocusonfitnessisasmuchaboutscienceandthefutureasitisaboutkeepinganyindividualastronautsreturnhome,and,moreimportantly,howtomaintainstrengthandfitnessforthetwoandahalfyearsormorethatitwouldtaketomakearound-triptoMars.63.Whatisthemajorchallengetoastronautswhentheysleepinspace?A.DecidingonapropersleeppositionB.ChoosingacomfortablesleepingbagC.SeekingawaytofallasleepquicklyD.Findingarighttimetogotosleep.64.Theastronautswillsufferfromacarbon-dioxideheadachewhen_____.A.