真题练习

555.They ______ on the program for almost one week before I joined them,and now we ______ on it as no good results have come out so far.

A.have worked;are still working

B.had worked;were still working

C.have been working;have worked

D.had been working;are still working

556.The young girl sitting next to me on the plane was very nervous.She _______ before.

A.hasn't flown

B.didn't fly

C.hadn't flown

D.wasn't flying

答案解析

555.答案是D;前半句为过去的过去，表示当时在进行；后半句为现在的情况，故选用单数形式。

556.答案是C;hadn't flown动作发生在nervous之前。