that从句在英语中具有多种用法，以下是对其用法及例子的详细归纳：
一、引导名词性从句
主语从句
- 用法：that在主语从句中作为连接词，不充当句子成分，只起到连接主句和从句的作用。主语从句通常位于句首，作为整个句子的主语。
- 例子：That he will come to the meeting is certain.（他会来参加会议是确定的。） That he is a teacher is known to all.（他是老师，这是众所周知的。） That she betrayed her friend is unforgivable.（她背叛朋友是不可饶恕的。） It is important that we respect each other.（我们彼此尊重是重要的。） It so happens that I know the man.（碰巧我认识那人。） That the earth turns around the sun is known to all.（地球围着太阳转这一点是众所周知的。）
宾语从句
- 用法：that引导的宾语从句常作为动词或介词的宾语，用于陈述一个事实或表达一个观点。
- 例子：I believe that he is honest.（我相信他是诚实的。） She said that she would come tomorrow.（她说她明天会来。） He knows that it is raining outside.（他知道外面正在下雨。） I will see to it that everything is ready.（我会注意把一切准备妥当的。） He admitted that he made a mistake.（他承认他犯了一个错误。） Do you know that she is coming?（你知道她要来吗？） There is no doubt that he is the best choice for this position.（无疑，他是这一职位的最佳人选。）
表语从句
- 用法：that引导的表语从句用于描述或解释主语的性质、状态或身份。
- 例子：The problem is that we don't have enough money.（问题是我们没有足够的钱。） The fact is that he didn't show up.（事实是他没有出现。） The trouble is that we are short of money.（困难就在于我们缺钱。） My belief is that honesty is the best policy.（我相信诚实是最好的策略。） The fact is that we need more time.（事实是我们需要更多的时间。）
同位语从句
- 用法：that引导的同位语从句用于对前面的名词进行进一步的解释或说明，两者在内容上等同。
- 例子：The news that he has won the prize is exciting.（他获奖的消息令人兴奋。） The news that he won the prize surprised everyone.（他获奖的消息让每个人都感到惊讶。）
二、引导定语从句
在限制性定语从句中，that作为关系代词指代先行词，并在从句中充当主语或宾语。这种从句通常用于限定先行词的范围，使其更加具体。
- 例子：The book that you lent me is very interesting.（你借给我的那本书很有趣。） The person that you met at the party is my brother.（你在聚会上遇到的人是我的兄弟。） The only thing that I can do is to have a rest.（我唯一能做的事就是休息。） The bike and its rider that had run over an old man were taken to the police station.（撞倒了一位老人的自行车和骑车人被带到了警察局。） The only thing that we can do is to give you some money.（我们唯一能做的就是给你一些钱。） The money that (which) is in the wallet is mine.（钱包里的钱是我的。） English is the most difficult subject that you will learn during these years.（英语是这几年你要学的最难的一门学科。） He is the last person (that) I want to see.（他是我最后一个想见的人。） It is the first American movie of this kind that I’ve ever seen.（这是我看过的第一部这种美国电影。） Do you know the things and persons that they are talking about?（你知道他们正在谈论的事情和人吗？） You should hand in all that you have.（你应该把你所有的都交上来。） Li Ming is the only one that wants to be a teacher.（李明是唯一一个想当老师的人。） Li Ming is one of the students that want to be teachers in our class.（李明是我们班想当老师的学生之一。） Edison built up a factory which produced things that had never been seen before.（爱迪生建了一个生产前所未见的东西的工厂。）
三、引导状语从句
that也可以与其他词构成短语，引导状语从句，表示原因、结果、条件、目的、让步等。
原因状语从句
- 例子：The reason that he was late is that he missed the bus.（他迟到的原因是他错过了公交车。） The fact that he didn't show up is that he was sick.（他没有出现的事实是他病了。） Now that they have taken matters into their hands, the pace of events has quickened.（他们既然已着手自己来处理问题，事态的进展也就加快了。）
结果状语从句
- 例子：He was so tired that he fell asleep immediately.（他太累了，立刻就睡着了。） The news was so surprising that everyone was shocked.（这个消息太令人震惊了，每个人都感到震惊。） He was so angry that he couldn't speak.（他气得说不出话来。）
条件状语从句
- 例子：If that is true, then I will believe you.（如果那是真的，那么我会相信你。） Provided that you help me, I will do it.（只要你帮助我，我就做这件事。）
目的状语从句
- 例子：I came here so that I could see you.（我来这里是为了见你。） She studied hard so that she could pass the exam.（她努力学习是为了通过考试。） Bring it nearer so that I may see it better.（拿近一点，好让我看清楚些。） She got up early, so that she caught the early bus.（她起得早，所以赶上了早班车。） In order that everybody should hear him, he spoke loudly.（他大声说话，为了使大家都能听得见。）
让步状语从句
- 例子：Even that he is rich, he is not happy.（即使他很富有，他也不快乐。） Although that she is young, she is very experienced.（尽管她很年轻，但她很有经验。） （注：在引导让步状语从句时，that的使用并不常见，更常用的是although、though、even though、while等词。）
注意事项
- 在使用that引导名词性从句时，要注意从句的时态和语态应与主句保持一致。
- 在限制性定语从句中，that不能省略。
- 当介词位于关系代词之前时，通常不使用that作为引导词（如不能说“the book that I am looking for it”中的that不能换成for which，但可以说“the book for which I am looking”或者省略关系代词直接说“the book I am looking for”）。
综上所述，that从句在英语中具有多种用法，掌握这些用法和相应的例子对于提高英语水平非常重要。
