Question

 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

Answer 1

 答案：A

解析：题干意思是：鲍伯打电话给他的妈妈说他不能进房子，因为他把钥匙忘在学校了。本句中的called标明动作发生在过去，而在电话之前忘记拿钥匙，所以应用had left表示过去的过去的动作。