Question

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

A．should have been doing	B．must have been doing
C．could have done	D．would have done

Answer 1

B

第一句話使用了一般過去時，由此可知第二句話是對過去事情的猜測，需用must have done.本題意為“我正在高速公路上行駛，這時一輛警車跟隨著著這輛車從旁邊經過。它們一定是以至少每小時150公里的速度行駛�！惫蔬xB。A項表示“本應該……”，C項表示“本能夠……”不合題意。