習慣上要用that引導的定語從句

指事物時，在下列情況下，人們通常用that，而不用which。

1. 當先行詞為不定代詞時：當先行詞是指物的all, little, few, much, any, anything, everything, nothing, none, the one時，或先行詞被all, little, few, much, any, every, no等修飾時，通常用that。如：

All [Everything] that can be done must be done. 凡能做的事都必須做。

There was little that the enemy could do but surrender. 敵人無法,只有投降了。

2. 當涉及序數詞或最高級時：當先行詞是序數詞或最高級形容詞時，或者先行詞被序數詞(包括last, next)、最高級形容詞及the only, the very等修飾時，通常用that。如：

This is the best dictionary that I’ve ever used. 這是我用過的最好的詞典。

The first thing that you should do is to work out a plan. 你應該做的第一件事是訂個計劃。

3. 當涉及the very, the only, the same時：當先行詞有the very, the only, the same 等修飾時，通常用that。如：

This is the only example that I know. 我知道的例子只有這一個。

Those are the very words that he used. 那是他的原話。

3. 當先行詞包括人和物時：此時通常用that。如：

They talked about the persons and things that most impressed them. 他們談論了使他們印象最深的人和事。