【题目】Helen ______ her keys in the office so she had to wait until her husband ______ home.
A. has left; comes B. left; had come
C. had left; came D. had left; would come
在线课程【答案】C
【解析】试题分析：句意：海伦把钥匙落在办公室了，所以她得等自己的丈夫回家
根据主句和从句两个动词的先后顺序可以判断，丢钥匙在前，回家再后，且都为过去式，所以前者用过去完成时，后者用一般过去式
考点:考察动词时态的用法