More than 20 people in traffic accidents last May.A. have died, forB. have died, sinceC.

More than 20 people in traffic accidents last May.
A. have died, for
B. have died, since
C. have been dead, since
D. have been dead, for

A. have died, forB. have died, since(答案→)C. have been dead, sinceD. have been dead, for解析：句意：自从去年五月，超过20 个人在交通事故中死亡。since last May，自从去年五月，一段时间。和一段时间连用，用延续性的动作或状态。die对应的延续性的状态是be dead.,动作从过去延续到现在，用现在完成时态，故选C。

谢谢了