Question

Bob called to tell his mother that he couldn’t enter the house, for he ________ his key at school

1. A.
   had left
2. B.
   would leave
3. C.
   was leaving
4. D.
   has left

Answer 1

A
該句句意為Bob打電話給他的媽媽，告訴她說他進不了房門，因為他把他的鑰匙忘在學校了。根據句意可知，把鑰匙忘在學校（leave）的動作發生在打電話（called）之前，called 是過去時，那么忘記鑰匙在學校leave就是發生在過去的過去，即過去完成時，故選擇A項。
【考點定位】考察時態。