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ID:30094812
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时间:2018-12-26
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2、owingtheoutlinegivenbelow: 1.近来一些城市政府实施多项举措降低公共交通票价,大力发展公共交通; 2.此措施带来的好处; 3.作为市民应如何响应政府的号召。 TheDecreaseofPublicTransportationTicketFare PartⅡReadingComprehension(SkimmingandScanning)(15minutes) Directions:Inthispart,youwillhave15minutestogooverth
3、epassagequicklyandanswerthequestionsonAnswerSheet1. Forquestions1-7,choosethebestanswerfromthefourchoicesmarkedA),B),C)andD). Forquestions8-10,completethesentenceswiththeinformationgiveninthepassage. TheDebateOverGeneticallyModifiedFoods Forthousan
4、dsofyearsfarmershaveusedaprocessofselectionandcrossbreedingtocontinuallyimprovethequalityofcrops.Traditionalbreedingmethodsareslow,requiringintensivelabor:whiletryingtogetadesirabletraitinabredspecies,undesirabletraitswillappearandfarmersmustcontinueth
5、eprocessoverandoveragainuntilalltheundesirablesarebredout.Incontrast,organismsacquireonespecificgeneorafewgenestogetherthroughgeneticmodification,withoutothertraitsincludedandwithinasinglegeneration.However,thistechnologytooisinherentlyunpredictableand
6、somescientistsbelieveitcanproducepotentiallydangerousresultsunlessbettertestingmethodsaredeveloped.Traditionalbreedingisbasedonsexualreproductionbetweenlikeorganisms.Thetransferredgenesaresimilartogenesinthecelltheyjoin.Theyareconveyedincompletegroupsa
7、ndinafixedsequencethatharmonizeswiththesequenceofgenesinthepartnercell.Incontrast,bioengineersisolateagenefromonetypeoforganismandcollectitrandomlyintotheDNAofadissimilarspecies,disruptingitsnaturalsequence.Oneofthemaindifferencesbetweenconventionaland
8、geneticallymodifiedcropsisthattheformerinvolvescrosseseitherwithinspeciesorbetweenverycloselyrelatedspecies.However,GMcropscanhavegenesfromcloselyrelatedspeciesorevenfrombacteriaandviruses.Benefits:onesideofthedebateEconomical?GMsupport
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