I was on the highway _______ this car went past followed by a police car. They _

题型：不详难度：来源：

I was on the highway _______ this car went past followed by a police car. They ______ at least 150 kilometers an hour.

A．when; should have been driving

B．while; would have driven

C．as; could have driven

D．when; must have been driving

答案

D

解析

考查连词和情态动词用法。因为go past（经过）是短暂性动词所以不能与while连用，while只能和延续性动词连用。When既可以与短暂性动词也可以与延续性动词连用。第二空表示对过去某时正在发生情况的肯定推测。句意：当一辆汽车从我旁边经过，后面跟着一辆警车的时候，我正在高速公路上。他们当时的速度至少150公里每小时。