Thefuturepopulationwillbeolderthantoday,andthisinturnwillchangethepatternsofsocialdemands.However,Mexicowillstillbefarfromthe"agingsocieties"thatwillmostlikelyprevail(占优势)intheindustrializedcountries.Inlessthan25years,thecountrywillhavetoaddalmostasmuchinfrastructureasithasalreadybuiltuptonow,simplytomaintainservicesandproductionatthecurrentlevels.Thiswillbeatremendouschallenge,althoughasimilaronewasfacedsuccessfullyintherecentpast,whenavailableinfrastructurewasdoubledintwodecadesorso.ItisnowonderthatmuchhasbeensaidabouttheneedtoreduceorpreferablyhaltMexico'spopulationcontrolwhichistakenforgrantedasbothgoodandnecessary.Ithasalsogainedsupportersinthedevelopingworld,andMexicoisnoexception.Buttheargumentsaboutpopulationarecomplicated,asthefollowingdiscussionillustrates.
EvenifMexico'spopulationreaches125millionbytheyear2010,itspopulationdensityisstillsmallerthanthe1985populationdensityofsome50countries.ByinternationalstandardsMexicowillstillnotbeoverpopulatedbytheyear2010.Ifwealthisgeneratedbypeople,themoreindividualsthereare,thegreaterthewealththatpotentiallycouldbegenerated.WhyshouldMexicocontrolitspopulationatdensitylevelsbelowthoseoftherichercountriesifmorepopulationrepresentsthepossibilityofgeneratingmorewealth?
Ontheotherhand,itisoftenpointedoutthatoncesustainability(支撑力)limitsarenearorarereached,therearedecreasingproductivitygains(or,perhapsmoreaccurately,increasingproductivelosses),andpeoplebecomeacostratherthananasset.Ifweassumethattherearesustainabilitylimitsandthatweareclosetoreachingtheselimitsataworldlevel,thenitisappropriatetocheckpopulationgrowth.
21.Accordingtothepassage,thepopulationargumentisfocusedon_______.
A.whethermorepeopleareapropertyoracost
B.whetherMexicoshouldcontrolitspopulationgrowthornot
C.whetherthedensityofpopulationinMexicoislargeorsmall
D.whatthestandardinternationalsustainabilitylimitis
22.WhichofthefollowingisTRUEaccordingtothefirstparagraph?
A.Mexicohassteppedintoanagingsociety.
B.ItisnotnecessaryforMexicotocontrolitspopulation.
C.Mexicopopulationisyoungerthanthatofdevelopedcountries.
D.ItisnotnecessaryforMexicotodevelopitsinfrastructure.
23.By"infrastructure"(Para.2)theauthormeans_______.
B.thebasicframeworkofacountry,suchasschools,services,etc.
24.Itmaybeinferredfromthe3rdparagraphthat_______.
A.itisn'tnecessaryforMexicotocontrolitspopulationgrowth
B.populationislikelytogrowataslowerpacethaninthepast
C.themorepeoplethereare,thegreaterthewealthpeoplecouldgenerate
D.Mexicoshouldcontrolitspopulationgrowthbecauseshebelongstothedevelopingcountries
25.Tocheckpopulationgrowthisnecessarywhen_______.
A.therearedecreasingproductivitygains
B.thereareincreasingproductivitylosses
C.weareclosetoreachingthesustainabilitylimitsataworldlevel
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