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第四部分：阅读理解（第31~45题，每题3分，共45分）
下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项
第一篇
GeneticEngineering
GeneticengineeringbeganwhentheDNAmolecule(分子), themostbasicunitoflife, wasfirstdescribedin 1953 byJamesWatsonandFrancisCrick. AnunderstandingofDNAledtothealteringofnormalcellreproduction. Experimentswithalteringhumancellsbeganin 1970. Inoneofthefirstexperiments, patientswereinjectedwithavirusthatwouldproducealife-savingenzyme, buttheirbodieswouldnotacceptit. In 1980 patientswithararebutfatalblooddiseasewereinjectedwithapurifiedgenethatwasclonedthroughDNAtechnology. Anotherfailure.
Geneticengineeringgotalegalboost(激励) in 1980. TheU.S. SupremeCourtsaidthatapatentcouldbegrantedonageneticallyengineeredoil-eatingbacterium(细菌). Thisbacteriumwouldhelpcleanupoilspills. Therulingencouragedcompaniestoinventnewlifeforms, andthreeimportantmedicalproductswerequicklydeveloped.
lHumaninterferon(干扰素)-- apossiblesolutiontosomecancersandviraldisease. Anewlyengineeredbacteriumproducedhumaninterferonasaby-product. Thisnewproductreducedthecostofinterferon.
lHumangrowthhormone-- forchildrenwhosebodiesdonotgrowtonormalheight. Anexpensivegrowthhormone(荷尔蒙) waspreviouslyproducedfromhumancadavers, butbychangingthegeneticmake-upofthesingle-cellbacteriumE. coli, andaffordablegrowthhormonecouldbeproduced.
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