【答案】More than 20 people in traffic accidents

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
答案
C
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。