3. I don’t know____ to visit the old man.

A. whether B. if C. that D. who

4.The soldiers soon reached( )was once an old temple(　)the villagers used as a school.

A.which;where B.what;which　C.where;which D.what;where

答：选B，动词reach后接宾语从句，从句缺少宾语，where不可，which引导宾语从句时表疑问含义“哪一个…”而此句中并非疑问含义，不知道哪一座庙宇，而是用what从句表陈述含义，意“过去的一座旧庙宇”;temple后为对其修饰的定语从句，用关系代词which代替，并在从句中作动词used的宾语，use sth. as…“把…用作…

宾语从句用作宾语。如：

Do you know where he lives?

定语从句相当于一个形容词，用于修饰前面的名词。如：

The student who answered the question was John. 回答问题的学生是John.

This is the man whom he is looking for.

Do you know the girl who is in red?