A、  B、  C、  C题目使用了一般疑问句，问的是“他”是否解释了整个程序。(A)虽然使用了同样的主语he，但是与问题不符。(B)的主语就与题目不符。(C)给出了肯定的回答，并说解释得相当清楚，因此为正确答案。

Can I leave a message for him?
(A) He should be back by Saturday.
(B) Certainly, I’ll pass it on.
(C) He had to leave in a hurry.

Did he explain the procedure to you?
(A) He said it is two blocks away.
(B) We’ll give details later.
(C) Oh yes, quite clearly.