By the time the tornado ended, more than 700 people .
A. have killed
B. had been killed
C. were killed
D. had killed
网友回答
A. have killed
(答案→)B. had been killed
C. were killed
D. had killed
解析：考查时态和语态。By+过去的时间，主句用过去完成时；by+将来的时间，主句用将来完成时。句意“到龙卷风结束的时候，已经有700多人被害。”根据ended可知，是过去的时间，主句用过去完成时；people和kill之间是动宾关系，应该用被动语态。故选B。