用法：
1、that作指示代詞
That is my book.那是我的書。
2、that作指示形容詞
We haven't found any solution to deal with that problem yet.我們仍未找到解決問題的辦法。
3、that作關系代詞引導定語從句
This is the sort of thing that Jeremy loves.這是杰里米喜歡的東西。
4、that作連詞
that可以作連詞引導各種名詞性從句，包括賓語從句、主語從句、同位語從句和表語從句。
1)that作連詞引導賓語從句
They have recommended that the site be closed and repaired. 他們建議將該處關閉并進行維修。
2)that作連詞引導主語從句
That you will win the medal seems unlikely. 你想獲得獎牌看起來是不可能的。
3)that作連詞引導同位語從句
The idea that modern art can only be seen in museums is mistaken. 現代藝術只能在博物館才能見到的想法是錯誤的。
4)that作連詞引導表語從句
One problem is that I don't look any different from other people. 有一個問題是我看起來和其它人沒有任何不同。
that還可以作連詞引導結果狀語從句，閱讀時需要留意這個用法。
What was the matter with the fellow that he looked so happy? 那人怎么回事，看起來這樣高興?
5、that作副詞
that和this都可以作副詞，用于修飾形容詞或修飾另一個副詞，表示“這么，那么，如此，這般”的意思，如:
It's about that long. 它大約有那么長。