Whileintegrasedeletesanimmunecell'sgeneticmaterialandreplacesitwithitsown,itactslike________inawordprocessor.

Imeant____youaboutit,butIforgottodoso.

翻译：

如今，中国正步入老龄化社会，因此独生子女一代面临着巨大的工作和生活压力。中国政府开始适当调整计划生育政策，允许一些家庭在特殊情况下生育二胎。但调查显示，很多夫妻迫于不断加重的经济压力，放弃生育二胎。因此，要从根本上解决老龄化的问题不能依靠出生率的上升，最有效的办法是建立有效的社会保障制度。

PartIIICloze

Directions:Therearetwentyblanksinthefollowingpassage.Foreachblanktherearefourchoices.ChoosetheonethatbestfitsintothepassageandthenmarksyouranswerontheAnswerSheet.

Therearetwofactorswhichdetermineanindividual’sintelligence.Thefirstisthesortofbrainheisborn61.Humanbrainsdifferconsiderably,62beingmorecapablethanothers.63nomatterhowgoodabrainhehastobeginwith,anindividualwillhavealoworderofintelligence64hehasopportunitiestolearn.Sothesecondfactoriswhat65totheindividual—thesortofenvironmentinwhichheisbrought66.Ifanindividualishandicapped(受阻碍)67,itislikelythathisbrainwill68todevelopandhewill69attainthelevelofintelligenceofwhichheis70.

Theimportanceofenvironmentindetermininganindividual’sintelligencecanbe71bythecasehistoryoftheidenticaltwins,PeterandJohn.Whenthetwinswerethreemonthsold,theirparentsdied,andtheyareplacedin72foster(寄养)homes.Peterwasrearedbyparentsoflowintelligenceinan73communitywithpooreducational74.John,75,waseducatedinthehomeofwell-to-doparentswhohasbeentocollege.Thisenvironmental76continueduntilthetwinswere77theirlateteens,78theyweregiventeststo79theirintelligence.John’sI.Q.(智商)was125,twenty-fivepointshigherthanthe80andfullyfortypointshigherthanhisidenticalbrother.

61.A.forB.byC.withD.in

62.A.mostB.someC.manyD.few

63.A.ButB.ForC.StillD.And

64.A.ifB.thoughtC.asD.unless

65.A.refersB.appliesC.happensD.concerns

66.A.aboutB.upC.forwardD.forth

67.A.relativelyB.intelligentlyC.regularlyD.environmentally

68.A.failB.helpC.manageD.stop

69.A.everB.neverC.evenD.nearly

70.A.ableB.capableC.availableD.acceptable

71.A.demonstratedB.deniedC.neglectedD.ignored

72.A.separateB.similarC.remoteD.individual

73.A.omittedB.isolatedC.enclosedD.occupied

74.A.possibilitiesB.opportunitiesC.capacitiesD.responsibilities

75.A.moreoverB.consequentlyC.thenD.however

76.A.exceptionB.divisionC.differenceD.alteration

77.A.inB.byC.atC.for

78.A.whileB.sinceC.whenD.because

79.A.estimateB.countC.decideD.measure

80.A.averageB.commonC.usualD.ordinary

Wecanbeginourdiscussionof“populationasglobalissue”withwhatmostpersonsmeanwhentheydiscuss“thepopulationproblem”:toomanypeopleonearthandatoorapidincreaseinthenumberaddedeachyear.Thefactsarenotindispute,Itwasquiterighttoemploytheanalogythatlikeneddemographicgrowthto“along,thinpowderfusethatburnssteadilyandhaltinglyuntilitfinallyreachesthechargeandexplodes.”

Tounderstandthecurrentsituation,whichischaracterizedbyrapidincreasesinpopulation,itisnecessarytounderstandthehistoryofpopulationtrends.Rapidgrowthisacomparativelyrecentphenomenon.Lookingbackatthe8,000yearsofdemographichistory,wefindthatpopulationshavebeenvirtuallystableorgrowingveryslightlyformostofhumanhistory.Formostofourancestors,lifewashard,oftennasty,andveryshort.Therewashighfertilityinmostplaces,butthiswasusuallybalancedbyhighmortality.Formostofhumanhistory,itwasseldomthecasethatoneintenpersonswouldlivepastforty,whileinfancyandchildhoodwereespeciallyriskyperiods.Often,societieswereincleardangerofextinctionbecausedeathratescouldexceedtheirbirthrates.Thus,thepopulationproblemthroughoutmostofhistorywashowtopreventextinctionofthehumanrace.

Thispatternisimportanttonotice.Notonlydoesitputthecurrentproblemsofdemographicgrowthintoahistoricalperspective,butitsuggeststhatthecauseofrapidincreaseinpopulationinrecentyearsisnotasuddenenthusiasmformorechildren,butanimprovementintheconditionsthattraditionallyhavecausedhighmortality.

Demographichistorycanbedividedintotwomajorperiods:atimeoflong,slowgrowthwhichextendedfromabout8,000BC.tillapproximatelyAD.1650.Inthefirstperiodofsome9600years,thepopulationincreasedfromsome8millionto500millionin1650.Between1650andthepresent,thepopulationhasincreasedfrom500milliontomorethan4billion.Anditisestimatedthatbytheyear2000therewillbe6.2billionpeoplethroughouttheworld.Onewaytoappreciatethisdramaticdifferenceinsuchabstractnumbersistoreducethetimeframetosomethingthatismoremanageable.Between8000BCand1650,anaverageofonly50,000personswasbeingaddedannuallytotheworld’spopulationeachyear.Atpresent,thisnumberisaddedeverysixhours.Theincreaseisabout80,000,000personsannually.

1.Whichofthefollowingdemographicgrowthpatternismostsuitableforthelongthinpowderfuseanalogy?

A.Avirtuallystableorslightlydecreasingperiodandthenasuddenexplosionofpopulation.

B.Aslowgrowthforalongtimeandthenaperiodofrapid,dramaticincrease.

C.Toomanypeopleonearthandafewrapidincreaseinthenumberaddedeachyear.

D.Alongperiodwhendeathratesexceedsbirthratesandthenashortperiodwithhigherfertilityandlowermortality.

2.Duringthefirstperiodofdemographichistory,societieswereoftenindangerofextinctionbecause___.

A.onlyoneintenpersonscouldlivepast40.

B.therewashighermortalitythanfertilityinmostplaces.

C.itwastoodangeroustohavebabiesduetothepoorconditions.

D.ourancestorshadlittleenthusiasmformorechildren.

3.Whichstatementistrueaboutpopulationincrease?

A.Theremightbeanincreaseof2.2billionpersonsfromnowtotheyear2000.

B.About50,000babiesareborneverysixhoursatpresent.

C.Between8000BCandthepresent,thepopulationincreaseisabout80,000,000personseachyear.

D.Thepopulationincreasedfasterbetween8000BCand1650thanbetween1650andthepresent.

4.Theauthorofthepassageintendsto___.

A.warnpeopleagainstthepopulationexplosioninthenearfuture.

B.comparethedemographicgrowthpatterninthepastwiththatafter1650.

C.findoutthecauseforrapidincreaseinpopulationinrecentyears.

D.presentusaclearandcompletepictureofthedemographicgrowth.

5.Theword“demographic”inthefirstparagraphmeans___.

A.statisticsofhuman.

B.surroundingsstudy.

C.accumulationofhuman.

D.developmentofhuman.