Question

—Why was he late for school yesterday?
— He overslept. By the time he got to the bus stop, the bus ________ already ______.

A．has; left

B．had; left

C．was; leaving

D．have; left

Answer 1

B

解析试题分析：句意：昨天他为什么迟到了？——他睡过头了。他到达公交车站时，公交车已经开走了。结合语境可知下文描述的是一直持续到过去某时的动作，故用过去完成时态，选B。
考点：考查动词的时态。