I was on the highway when this car went past fllowed by a police car .

Question

They_____ at least 150 kilometers an hours.
A.should have been going B.must have been going
C.could have gone D.would have gone
请详细解答一下为什么，谢谢！

Answer 1

选 B.must have been going

理由：上文提供了证据“I was on the highway when this car went past fllowed by a police car",即有把握的肯定推测，用must。因为是对过去某一时刻的推测，用过去完成进行时，have been going。

Answer 2

B.must have been going,对过去发生的事情的判断

Answer 3

B、must加have done 表示对过去动作的猜测