1
reporting verb + that + clause
在口语中，that 常可省略。
She said that she was tired.
她说她累了。
（用于引导名词性从句，无实义）
先理解核心含义，再看它在真实句子里的用法。
（用于引导名词性从句，无实义）
Introducing a clause that functions as a noun clause, such as the subject or object of a verb, a complement of an adjective or verb, or in apposition to a noun.
She said that she was tired.
她说她累了。
引导宾语从句时，口语中常省略that。
引导动词宾语从句,尤其是报道动词或表达信念、知识、感知的动词
Introducing a clause that is the object of a verb, especially a reporting verb or verb expressing belief, knowledge, perception, etc.
引导动词主语从句,尤其是“是”动词或表达判断、意见的动词
Introducing a clause that is the subject of a verb, especially the 'be' verb or a verb expressing judgement, opinion, etc.
引导形容词或被动分词的补语从句
Introducing a clause that complements an adjective or passive participle.
引导修饰副词的从句
Introducing a subordinate clause modifying an adverb.
She told me that the meeting starts at nine.
她告诉我会议九点开始。
It is clear that we need more time.
很明显我们需要更多时间。
The box was so heavy that I couldn't lift it.
这个箱子太重了，我抬不动。
在口语中，that 常可省略。
She said that she was tired.
她说她累了。
这里的 that 从句说明形容词或分词所表示感受的内容。
I am glad that you came.
我很高兴你来了。
这种主语从句较正式，日常常改用 it 作形式主语。
That she won the prize is surprising.
她赢得奖项这件事令人惊讶。
so...that 表示“如此……以至于”，引导结果状语从句。
It was so cold that we stayed indoors.
天气太冷了，我们待在屋里。
Not this
He was late was a problem.
Use this
That he was late was a problem.
英语中从句作主语时必须用从属连词 that 引导，汉语则靠语序直接说出'他迟到是个问题'，学习者容易漏掉 that；加上 that 后，'That he was late' 是合法的主语从句，整个句子结构才成立。
Not this
The reason he was late is because he missed the bus.
Use this
The reason he was late is that he missed the bus.
reason 本身已包含'原因'之意，表语从句中应使用 that 来直接说明具体原因，不能再接 because，否则语义重复且不符合标准书面语。
Not this
I want to know that he will come.
Use this
I want to know whether he will come.
want to know 表达的是'去了解一件未知的事'，后面的从句是间接疑问句，须用 whether 或 if 引导；that 从句用于陈述已知信息，用在这里会改变原意。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
以便，为了
She left early so that she could catch the train.
她早早出发以便能赶上火车。
如此…以至于
The damage was such that it could not be repaired.
损坏如此严重，以至于无法修复。
因为，在于
This plan is better in that it costs less.
这个计划更好，因为花费更少。
既然
Now that you're here, let's start the meeting.
既然你来了，我们开始开会吧。
鉴于，考虑到
Given that it's raining, we should stay indoors.
鉴于正在下雨，我们应该待在室内。
除了…之外；只是
The room is quiet except that the clock ticks loudly.
房间里很安静，只是时钟滴答声很响。
以便；所以
She studied hard so that she could pass the exam.
她努力学习以便能通过考试。
既然
Now that everyone is here, let's begin.
既然大家都到了，我们开始吧。
因为；在于
This design is better in that it uses less material.
这个设计更好，因为它使用较少的材料。
我知道我一无所知。
This well-known saying is linked to the Greek philosopher Socrates; it suggests that realizing one's own ignorance is a step toward wisdom.
这句名言与希腊哲学家苏格拉底有关；它表明认识到自己的无知是走向智慧的一步。
我们认为这些真理是不言而喻的：人人生而平等。
This phrase from the U.S. Declaration of Independence (1776) expresses the founders' belief in the equality of all people.
这句短语出自1776年的美国《独立宣言》，表达了开国者们对人人平等的信念。
Use that naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
把引导从句的 that 想成一根手指：它一出现就指着后面整句——I think (that) he is right。
语域：neutral 常见场景：日常对话、新闻报道、学术写作 that 作连词引导名词性从句或结果状语从句时，在口语和书面语中都很常见，通常没有明显的正式或非正式区分；正式写作中有时会因句式需要保留或省略 that，这更多是风格选择而非严格的语体差别。
引导名词性从句或目的、结果、原因状语从句；常用于'so that'结构中。
Dictionary facts from DICTIONARY_API_DEV, ECDICT, WIKTIONARY.