More than 20 people in traffic accidents last week.A. died; forB. have been dead; sinceC

问题补充：

More than 20 people in traffic accidents last week.

A. died; for

B. have been dead; since

C. have died; for

D. have been dead, for

答案：

A. died; for

(答案→)B. have been dead; since

C. have died; for

D. have been dead, for

解析：句意：从上周到现在有超过20人在交通事故中丧失。现在完成时可以用来表示发生在过去某一时刻的,持续到现在的动作（用行为动词表示）或状态（be动词表示）常与for（+时间段）,since（+时间点或过去时的句子）连用. 现在完成时中，非延续性动词不能与for和since引导的表示一段时间的状语连用，通常是用相应的延续性动词来代替。die对应的延续性状态是be dead.故选B。