Whileintegrasedeletesanimmunecell'sgeneticmaterialandreplacesitwithitsown,itactslike________inawordprocessor.
a cut and paste operation
暂无解析
Onceitwaspossibletodefinemaleandfemaleroleseasilybythedivisionoflabor.Menworkedoutsidethehomeandearnedtheincometosupporttheirfamilies,whilewomencookedthemealsandtookcareofthehomeandthechildren.Theseroleswerefirmlyfixedformostpeople,andtherewasnotmuchopportunityforwomentoexchangetheirroles.Butbythemiddleofthiscentury,men’sandwomen’sroleswerebecominglessfirmlyfixed.
Inthe1950s,economicandsocialsuccesswasthegoalofthetypicalAmerican.Butinthe1960sanewforcedevelopedcalledthecounterculture.Thepeopleinvolvedinthismovementdidnotvaluethemiddle-classAmericangoals.Thecounterculturepresentedmenandwomenwithnewrolechoices.Takingmoreinterestinchildcare,menbegantosharechild-raisingtaskswiththeirwives.Infact,someyoungmenandwomenmovedtocommunalhomesorfarmswheretheeconomicandchildcareresponsibilitiesweresharedequallybybothsexes.Inaddition,manyAmericansdidnotvaluethetraditionalmaleroleofsoldier.SomeyoungmenrefusedtobedraftedassoldierstofightinthewarinVietnam.
Intermsofnumbers,thecounterculturewasnotaverylargegroupofpeople.ButitsinfluencespreadtomanypartsofAmericansociety.Workingmenofallclassesbegantochangetheireconomicandsocialpatterns.Industrialworkersandbusinessexecutivesalikecutdownon“overtime”worksothattheycouldspendmoreleisuretimewiththeirfamilies.Somedoctors,lawyers,andteachersturnedawayfromhighpayingsituationstopracticetheirprofessionsinpoorerneighborhoods.
Inthe1970s,thefeministmovement,orwomen’sliberation,producedadditionaleconomicandsocialchanges.Womenofallagesandatalllevelsofsocietywereenteringtheworkforceingreaternumbers.Mostofthemstilltooktraditionalwomen’sjobsaspublicschoolteaching,nursing,andsecretarialwork.Butsomewomenbegantoentertraditionallymaleoccupations:policework,banking,dentistry,andconstructionwork.Womenwereaskingforequalwork,andequalopportunitiesforpromotion.
Todaytheexpertsgenerallyagreethatimportantchangesaretakingplaceintherolesofmenandwomen.Naturally,therearedifficultiesinadjustingtothesetransformations.
1.WhichofthefollowingbestexpressthemainideaofParagraph1?
A.Womenusuallyworkedoutsidethehomeforwages.
B.Menandwomen’sroleswereeasilyexchangedinthepast.
C.Men’srolesathomeweremorefirmlyfixedthanwomen’s.
D.Menandwomen’sroleswereusuallyquiteseparatedinthepast.
2.WhichsentencebestexpressesthemainideaofParagraph2?
A.Thefirstsentence.
B.Thesecondandthethirdsentences.
C.Thefourthsentence.
D.Thelastsentence.
3.Inthepassagetheauthorproposesthatthecounterculture___.
A.destroyedtheUnitedStates.
B.transformedsomeAmericanvalues.
C.wasnotimportantintheUnitedStates.
D.broughtpeoplemoreleisuretimewiththeirfamilies.
4.Itcouldbeinferredfromthepassagethat___.
A.menandwomenwillneversharethesamegoals.
B.somemenwillbewillingtoexchangetheirtraditionalmaleroles.
C.mostmenwillbehappytosharesomeofthehouseholdresponsibilitieswiththeirwives.
D.moreAmericanhouseholdsareheadedbywomenthaneverbefore.
5.Thebesttitleforthepassagemaybe___.
A.ResultsofFeministMovements
B.NewinfluenceinAmericanLife
C.CountercultureandItsconsequence
D.TraditionalDivisionofMaleandFemaleRoles.
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.
Whyaretoday'soldermiddle-agedandelderlybecomingthenewwinners?