－Why are you looking so worried? Is there anything I can do for you?－The computer break do

问题补充：

－Why are you looking so worried? Is there anything I can do for you?

－The computer break down when I nearly finished my composition.

A. can

B. should

C. must

D. dare

答案：

A. can

B. should

(答案→)C. must

D. dare

解析：考察情态动词辨析。Can可能；should应该；must必须，一定，非得，偏偏；dare敢；句意：—为什么你看上去如此担忧？我可以为你做什么？—当我写完作文的时候，计算机偏偏在那个时候坏了。根据句意说明must表示的是偏偏。故C正确。