大学英语二2、2Youhavebeenbadlyinjuredinacaraccident.Itisnecessarytogiveyouabloodtransfusionbecauseyoulostagreatdealofbloodintheaccident.However,specialcareshouldbetakeninselectingnewbloodforyou.Ifthebl

　　大学英语二2、2

　　Youhavebeenbadlyinjuredinacaraccident.Itisnecessarytogiveyouabloodtransfusionbecauseyoulostagreatdealofbloodintheaccident.However,specialcareshouldbetakeninselectingnewbloodforyou.Ifthebloodistoodifferentfromyourown,thetransfusioncouldkillyou.Therearefourbasictypesofblood:A,B,AB,andO.Asimpletestcanindicateaperson’sbloodtype,which,likehairandheight,isinheritedfromparents.Becauseofsubstancescontainedineachtype,thefourgroupsmustbetransfusedcarefully.Basically,AandBcannotbemixed.AandBcannotreceiveAB,butABmayreceiveAorB.Ocangivetoanyothergroup;henceitisoftencalledtheuniversaldonor.Fortheoppositereason,ABissometimescalledtheuniversalrecipient.However,becausesomanyreactionscanoccurintransfusions,patientsusuallyreceiveonlysaltorplasma(liquid)untiltheirbloodcanbematchedasexactlyaspossibleinthebloodbankofahospital.Inhisway,itispossibletoavoidanybadreactionstothetransfusion.Thereisarelationshipbetweenyourbloodtypeandyournationality.AmongEuropeansandpeopleofEuropeanancestry,about42percenthavetypeAwhile45percenthavetypeO.TherarestistypeAB.Otherraceshavedifferentpercentages.Forexample,someAmericanIndiangroupshavenearly100percenttypeO.

　　2)、Theword“hence”inline8means_________

　　选项:

　　a、always

　　b、often

　　c、therefore

　　d、seldom

　　选哪个