定語從句只能用which的情況：1.在介詞后面的關(guān)系代詞用which而不能用that。即“介詞+which（代物）”；2.在非限定性定語從句中不能用that等。

定語從句中只能用which，不能用that的幾種情況

1.在介詞后面的關(guān)系代詞用which而不能用that。即“介詞+which（代物）”例如：

The picture for which he paid $1,000 was once owned by a duke.

他花了1000美元買下的畫曾為一名公爵所擁有。

2.在非限定性定語從句中不能用that。例如：

Crusoe's dog, which was very old now, became ill and died.

克魯索的狗，現(xiàn)在已經(jīng)很老了，病死了。

3.有兩個定語從句，其中一個關(guān)系代詞已有which，另一個可以用that。相反，如果其中一個為that，另一個可以用which。

Edison built up a factory which produced things that had never been seen before.

愛迪生辦了一個工廠，生產(chǎn)過去從未見過的東西。