Aabruptadj.生硬的；突然的；唐突的；陡峭的describessomethingthatissuddenandunexpected,andoftenunpleasant 　　B.quickadj.快的；迅速的,敏捷的；灵敏的happeningordonewithgreatspeed,orlastingonlyashorttime 　　C.Immediateadj.立即的；直接的；最接近的happeningordonewithoutdelayorverysoonaftersomethingelse 　　D.instantadj.立即的；紧急的；紧迫的happeningimmediately,withoutanydelay 　　从manypassengersfallofftheirseats判断,火车是在人们毫无思想准备的情况下突然停的,所以应选A： 　　1.Thetraincametoanabruptstop,makingmanypassengersfallofftheirseats. 　　火车突然忽然一下子停了,很多乘客都从座位上跌落下来.