某同学在进行组织培养过程中,发现只分裂而不分化出芽和根,可能原因是()
A、未见阳光Modern____perhapscausesmoreproblemsthanitsolves.
Scatteredthroughtheseasoftheworldarebillionsoftonsofsmallplantsandanimalscalledplankton.Mostoftheseplantsandanimalsaretoosmallforthehumaneyetosee.Theydriftaboutlazilywiththecurrents,providingabasicfoodformanylargeranimals.Planktonhasbeendescribedastheequivalentofthegrassesthatgrowonthedrylandcontinents,andthecomparisonisanappropriateone.Inpotentialfoodvaluehowever,planktonfaroutweighsthatofthelandgrasses.Onescientisthasestimatedthatwhilegrassesoftheworldproduceabout49billiontonsofvaluablecarbohydrateseachyear.Thesea’splanktongeneratesmorethantwiceasmuch.
Despiteitsenormousfoodpotential,littleeffortwasmadeuntilrecentlytofarmplanktonaswefarmgrassesonland.Nowmarinescientistshaveatlastbeguntostudythispossibility,especiallyasthesea’sresourcesloomevenmoreimportantasameansoffeedinganexpandingworldpopulation.
Nooneyethasseriouslysuggestedthat“planktonburgers”maysoonbecomepopulararoundtheworld.Asapossiblefarmedsupplementaryfoodsource,however,planktonisgainingconsiderableinterestamongmarinescientists.
Onetypeofplanktonthatseemstohavegreatharvestpossibilitiesisatinyshrimplikecreaturecalledkrill.Growingtotwoorthreeincheslong,krillprovidethemajorfoodforthegiantbluewhale,thelargestanimalevertoinhabittheEarth.Realizingthatthiswhalemaygrow100feetandweigh150tonsatmaturity,itisnotsurprisingthateachonedevoursmorethanonetonofkrilldaily.
Krillswimaboutjustbelowthesurfaceinhugeschoolssometimesmileswide,mainlyinthecoldAntarctic.Becauseoftheirpinkcolor,theyoftenappearasasolidreddishmasswhenviewedfromashiporfromtheair.Krillareveryhighinfoodvalue.Apoundofthesecrustaceanscontainsabout460calories—aboutthesameasshrimporlobster,towhichtheyarerelated.
Ifthekrillcanfeedsuchhugecreaturesaswhales,manyscientistsreason,theymustcertainlybecontendersasnewfoodsourceforhumans.
1.Whichofthefollowingbestportraystheorganizationofthepassage?
A.Theauthorpresentstheadvantagesanddisadvantagesofplanktonasafoodsource.
B.Theauthorquotespublicopiniontosupporttheargumentforfarmingplankton.
C.Theauthorclassifiesthedifferentfoodsourcesaccordingtoamountofcarbohydrate.
D.Theauthormakesageneralstatementaboutplanktonasafoodsourceandthenmovestoaspecificexample.
2.Accordingtothepassage,whyisplanktonregardedtobemorevaluablethanlandgrasses?
A.Itiseasiertocultivate.
B.Itproducesmorecarbohydrates.
C.Itdoesnotrequiresoil.
D.Itismorepalatable.
3.Whydoestheauthormention“planktonburgers”?
A.Todescribetheappearanceofonetypeofplankton.
B.Toillustratehowmuchplanktonawhaleconsumes.
C.Tosuggestplanktonasapossiblefoodsources.
D.Tocomparethefoodvaluesofbeefandplankton.
4.Whatismentionedasoneconspicuousfeatureofkrill?
A.Theyarethesmallestmarineanimals.
B.Theyarepinkincolor.
C.Theyaresimilarinsizetolobsters.
D.Theyhavegrasslikebodies.
5.Theauthormentionsallofthefollowingasreasonswhyplanktoncouldbeconsideredahumanfoodsourceexceptthatitis___.
A.highinfoodvalue.
B.inabundantsupplyintheoceans.
C.anappropriatefoodforotheranimals.
D.freeofchemicalsandpollutants.
Marytiptoedoverandtooktheclockawaybecauseshehatedtohearit()whenshewastryingtogotosleep.
PartIIVocabularyandStructure
Directions:Inthisparttherearefortyincompletesentences.Eachsentenceisfollowedbyfourchoices.ChoosetheonethatbestcompletesthesentenceandthenmarkyouranswerontheAnswerSheet.
21.Theteacherthestudentsonatourthroughtheartmuseum.
A.madeB.indicatedC.forcedD.took
22.Tom’sparentsdiedwhenhewasachild,sohewasbyhisrelatives.
A.grownupB.broughtupC.raisedD.fedup
23.Hereismycard.Let’skeepin.
A.touchB.relationC.connectionD.friendship
24.Sofarthereisnoproofpeoplefromotherplanetsdoexist.
A.whichB.howC.whatD.that
25.Thenewspapersreportedyesterdayseveralontheboundariesofthesetwocountries.
A.incidentsB.happeningsC.eventsD.accidents
26.We’veworkedouttheplanandnowwemustputitinto.
A.factB.realityC.practiceD.deed
27.Hedidn’tandsohefailedtheexamination.
A.workenoughhardB.hardworkenoughC.hardenoughworkD.workhardenough
28.NotuntilMr.SmithcametoChinawhatkindofcountrysheis.
A.heknewB.hedidn’tknowC.didheknowD.hecouldn’tknow
29.Scientistssayitmaybetenyearsthismedicinewasputtouse.
A.sinceB.beforeC.afterD.when
30.Insomecountries,iscalled“equality”doesnotreallymeanequalrightsforallpeople.
A.thatB.whatC.whichD.how
31.Wedidn’tknowhistelephonenumber,otherwisewehim.
A.wouldtelephoneB.wouldhavetelephone
C.hadtelephonedD.musthavetelephoned
32.We’vemissedthelastbus,I’mafraidwehavenobuttotakeataxi.
A.wayB.possibilityC.choiceD.selection
33.Luckily,mostsheepthefloodlastmonth.
A.enduredB.survivedC.livedD.passed
34.Myparentsalwaysletmehavemyownofliving.
A.wayB.methodC.mannerD.fashion
35.Likeotherlanguageskills,readingrequirespractice.
A.themostofB.muchoftheC.mostoftheD.moreofthe
36.Itisonlythroughpracticeonewillbeabletoswimskillfully.
A.whatB.whoC.thatD.which
37.Thebrainiscapableofignoringpainmessageoftoconcentrateonotheractivities.
A.itallowedB.isitallowedC.allowedD.allowedit
38.Don’tworry,Ihavealreadythemthedecision.
A.informed;withB.informed;ofC.informed;forD.informed;that
39.Thechildwassorryhismotherwhenhearrivedatthestation.
A.tomissB.havingmissedC.missingD.tohavemissed
40.Iwonderwhyhetodiscusstheproblematthemeeting.
A.declinedB.rejectedC.refusedD.delayed
41.Youcanhangupwhatyoulikeonthesewalls.
A.bareB.emptyC.blankD.vacant
42.Accordingtoa,themajoritywouldratherhavenewspaperswithoutagovernmentthanagovernmentwithoutnewspapers.
A.electionB.campaignC.pollD.vote
43.Thepopulationofthevillagehasdecreased150to500.
A.inB.atC.byD.with
44.ItseemsthatthereisthatIcan’tdo.
A.nothingB.anythingC.everythingD.none
45.Theyareoftencaringmoreaboutanimalsthanhumanbeings.
A.accusedifB.accusedwithC.chargedofD.chargedfor
46.agoodbeginningismade,thewordishalfdone.
A.AssoonasB.WhileC.AsD.Once
47.Georgecouldnothisfoolishmistake.
A.accountinB.countonC.countforD.accountfor
48.Wecameintothisfieldlate,sowemustworkhardtothelosttime.
A.makeupforB.makeoutC.keepupwithD.putupwith
49.Thenewlawwillcameintoonthedayitispassed.
A.effectB.useC.serviceD.existence
50.Wecanseparatethemixtureintothepurechemicalcompoundsitiscomposed.
A.inwhichB.ofwhatC.ofwhichD.fromwhich
51.Mrs.Lincolnhasthatsheisunabletogetajob.
A.suchsmalleducationB.solittleeducation
C.asuchlittleeducationD.asosmalleducation
52.Shecan’tpreventherlittleboyshootingbirds.
A.from;toB.on;atC.with;upD.from;at
53.Manycountriesareincreasingtheiruseofnaturalgas,windandotherformsof.
A.energyB.sourceC.powerD.material
54.Adarkenedskyinthedaytimeisusuallyandindicationthatastormis.
A.possiblecomingB.abouttotakeplace
C.closebyD.expectedtobesevere
55.Weallknowthatspeaklouderthanwords.
A.movementsB.performanceC.operationsD.actions
56.,hecouldnotcoverthewholedistanceinfifteenminutes.
A.FastashecanB.Ashecanranfast
C.IfhecanranfastD.Sinceheranfast
57.Agriculturalproductioninthatcountryhasincreasedinrecentyears.
A.vastlyB.strikinglyC.considerablyD.extremely
58.Peterhasplannedtosomemoneyeverymonthsothathecanbuyausedcarnextyear.
A.setasideB.setupC.setinD.setalong
59.AlthoughIspoketohimmanytimes,henevertookanyofwhatIsaid.
A.attentionB.noticeC.warningD.observation
60.Theyovercameallthedifficultiesandfulfilledtheplanthreemonthsaheadoftime,issomethingwehadnotexpected.
A.thatB.whatC.itD.which
TEXTC
Therearetwofactorswhichdetermineanindividual'sintelligence.Thefirstisthesortofbrainheisbornwith.
Humanbrainsdifferconsiderably,somebeingmorecapablethanothers.Butnomatterhowgoodabrainhehas
tobeginwith,anindividualwillhavealoworderofintelligenceunlesshehasopportunitiestolearn.Sothe
secondfactoriswhathappenstotheindividual—thesortofenvironmentinwhichheisbroughtup.Ifan
individualishandicapped(不利)environmentally,itislikelythathisbrainwillfailtodevelopandhewillnever
attainthelevelofintelligenceofwhichheiscapable.Theimportanceofenvironmentindetermininganindividual'sintelligencecanbedemonstratedbythecasehistoryoftheidenticaltwins,PeterandMark.Beingidentical,thetwinshadidenticalbrainsatbirth,andtheirgrowthprocesseswerethesame.Whenthetwinswerethreemonthsold,theirparentsdied,andtheywere
placedinseparatefoster(抚养)homes.Peterwasraisedbyparentsoflowintelligenceinanisolatedcommunity
withpooreducationalopportunities.Markwasrearedinthehomeofwell-to-doparentswhohadbeentocollege.Hewasreadtoasachild,senttogoodschools,andgiveneveryopportunitytobestimulated
intellectually.Thisenvironmentaldifferencecontinueduntilthetwinswereintheirlateteens,whentheywere
giventeststomeasuretheirintelligence.Mark'sI.Q.was125,twenty-fivepointshigherthantheaverageand
fullyfortypointshigherthanhisidenticalbrother.Givenequalopportunities,thetwins,havingidenticalbrains,
wouldhavetestedatroughlythesamelevel.
11.Thisselectioncanbestbetitled____________.
A.MeasuringYourIntelligence
B.IntelligenceandEnvironment
C.TheCaseofPeterandMark
D.HowtheBrainInfluencesIntelligence
12.Thebeststatementofthemainideaofthispassageisthat_______.
A.humanbrainsdifferconsiderably
B.thebrainapersonisbornwithisimportantindetermininghisintelligence
C.environmentiscrucialindeterminingaperson'sintelligence
D.personshavingidenticalbrainswillhaveroughlythesameintelligence
13.Accordingtothepassage,theaverageI.Q.is_______.
A.85.B.100C.110D.125
14.Thecasehistoryofthetwinsappearstosupporttheconclusionthat_______.
A.individualswithidenticalbrainsseldomtestatthesamelevelB.anindividual'sintelligenceisdeterminedonlybyhisenvironment
C.lackofopportunityblocksthegrowthofintelligence
D.changesofenvironmentproducechangesinthestructureofthebrain
15.Thispassagesuggeststhatanindividual'sI.Q._______.
A.canbepredictedatbirth
B.staysthesamethroughouthislife
C.canbeincreasedbyeducation
D.isdeterminedbyhischildhood