When where he had put the book he kept silent.A. askB. askingC. to askD. asked

问题补充：

When where he had put the book, he kept silent.

A. ask

B. asking

C. to ask

D. asked

答案：

A. ask

B. asking

C. to ask

(答案→)D. asked

解析：考查省略句。当状语从句的主语和主句主语一致时，我们可以把状语从句的主语和系动词一起省略。本题省略了he was;句意：当他被问把书放到那里的时候，他什么都不说。