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

问题补充：

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

A. had left

B. would leave

C. was leaving

D. has left

答案：

(答案→)A. had left

B. would leave

C. was leaving

D. has left

解析：该句句意为Bob打电话给他的妈妈，告诉她说他进不了房门，因为他把他的钥匙忘在学校了。根据句意可知，把钥匙忘在学校（leave）的动作发生在打电话（called）之前，called 是过去时，那么忘记钥匙在学校leave就是发生在过去的过去，即过去完成时，故选择A项。

【考点定位】考察时态。