“that”這個詞在英語中很常見，有很多不同的用法。你注意到'that'在前面句子中的用法了嗎?在這種情況下，'that'被用作關係代詞作補語。通常，‘that’可以用在句子中，也可以完全省去。例如，許多學英語的學生知道，根據具體情況，可以省略'that '。這篇關於“that”用法的指南將幫助你理解什麼時候該用這個詞，什麼時候可以不用它。
That在句子開頭用作限定詞，表示離説話人很遠的一個賓語。注意that作為限定詞的複數形式是those。'That'和'those'通常與'there'連用，表示賓語離説話人不近。
例如：
That's my friend Tom over there.
That's a pencil you have in your hand.
Those paintings are by Cezanne.
That is my house on the corner of the street.
'That'可以用作關係代詞連接兩個從句。在這種情況下，'that'也可以被'who'或'which '代替。
例如: That = Which
Tom bought the apples that the man was selling.
OR
Tom bought the apples which the man was selling.
例如: That = Who
Peter invited the boy that was new in class.
OR
Peter invited the boy who was new in class.
'That'可以用在充當動詞賓語的從句中。
例子：
Jennifer hinted that she would be late for class.
Doug knew that he needed to hurry up.
The teacher suggested that we finish our homework.
'That'可以用在從句中，跟在名詞或形容詞後面作補語。補語有助於提供有關名詞或形容詞的附加信息。它回答了“為什麼”的問題。
例如：
Peter is upset that his sister wants to drop out of high school.
Mr. Johnson appreciates our efforts that have brought in a lot of donations.
She is certain that her son will be accepted to Harvard.
That從句可以引入一個短語作為句子的主語。“that”從句的這種用法有點正式，在日常用語中並不常見。
例如
That it is so difficult is hard to understand.
That Mary feels so sad is very upsetting.
That our teacher expects us to do two hours of homework every day is crazy!
事實是……
與that從句作主語有關的是更常用的短語“the fact that…”來引出一個句子。雖然這兩種形式都是正確的，但是用“the fact that....”開頭的句子更常見。
例如
The fact that he wants to see you should make you happy.
The fact that unemployment is still high proves what a difficult economy this is.
The fact that Tom passed the test shows how much he has improved.
有很多與that連用的複合連詞。這些表達通常在正式英語中使用，包括:
“in order that”“so that”“provided that”“in case that”“now that”“given that”
例如
He purchased the computer so that he might improve his typing.
Susan told him she would marry him providing that he found a job.
Alice feels happy now that she has moved into a new home.
在轉述動詞say (That)、tell someone (That)、regret (That)、imply (That)等後，可以省略That。
例如：
Jennifer said (that) she was in a hurry.
Jack told me (that) he wanted to move to New York.
The boss implied (that) the company was doing very well.
在回答“why”這個問題時，有些形容詞後面可以跟“that”。'That'可以放在形容詞後面。
I'm happy (that) you found a new job.
She's sad (that) he's going to move to New York.
Jack is anxious (that) he didn't pass the test.
當that作為從句的賓語時，省略它是很常見的。
He invited the boy (that) he met on the train.
Shelly purchased the chair (that) she had seen at the auction.
Alfred wants to read the book (that) Jane recommended.
