Whileintegrasedeletesanimmunecell'sgeneticmaterialandreplacesitwithitsown,itactslike________inawordprocessor.

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.

PartIVTranslation

Directions:TranslatethefollowingsentencesintoEnglish.

每个人手里都有一张申请表，但却都不知道送往哪个办公室。

Whyaretoday'soldermiddle-agedandelderlybecomingthenewwinners?

翻译：

最近，一些地方大学开始将方言列为某些学生的必修课程，学生们要学习当地方言，然后被评分以作为毕业的依据之一。一方面，支持此种做法的人认为，将方言列为必修课可防止其消失，从而使当地传统文化和文化多样性得以弘扬，同时城市独特的个性得以保留。另一方面，反对此种做法的人争论说，当地学生与外地学生相比有很多绝对优势，因此将方言列为必修课会引起教育不公平的问题。而且，将方言列为必修课程还会引起一些其他问题，如教材使用、师资问题和考试标准等。在我看来，方言作为传统文化不可缺少的一部分和一种交流工具，可以让学生自愿学习和使用，而不是强制完成。