Subordinating conjunctions introduce a dependent clause and connect it to an independent clause. They show how one idea depends on another by adding a relationship such as time, cause, condition, contrast, purpose, or concession. The dependent clause cannot stand alone as a complete sentence, so it needs the main clause to complete the meaning.

A dependent clause can come before or after the independent clause. When the dependent clause comes first, it sets context and the main clause delivers the key point. When it comes second, it adds an explanation or condition after the main idea.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 例子
If the dependent clause comes first, use a comma after it	📌 如果从属从句先行，请在其后用逗号	Because it was raining, we stayed inside.	📝 因为下雨，我们待在室内。
If the dependent clause comes after the main clause, usually no comma	📌 如果从属从句在主句之后，通常不加逗号	We stayed inside because it was raining.	📝 我们待在室内，因为下雨了。
Use a comma before the dependent clause mainly when it is nonessential or strongly contrastive	📌 仅在从句非必要或与主句强烈对比时，在它前面使用逗号	I went anyway, although I was tired.	📝 尽管我很累，我还是去了。

Time subordinators explain when something happens relative to something else. They can show sequence, simultaneity, or a deadline. Choose the conjunction that best matches the timing relationship you want to express.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
when	⏱️ when	at the time that	⏱️ 在……时	Call me when you arrive.	🗣️ 当你到达时给我打电话。
while	⏱️ while	during the same time as	⏱️ 与……同一时间	I read while she cooked.	🗣️ 我在她做饭时看书。
before	⏱️ before	earlier than	⏱️ 在……之前	Wash your hands before you eat.	🗣️ 在你吃饭前请洗手。
after	⏱️ after	later than	⏱️ 比……晚	We left after the meeting ended.	🗣️ 会议结束后我们离开。
until	⏱️ until	up to the time that	⏱️ 直到……	Stay here until I come back.	🗣️ 我等你回来之前待在这里。
as soon as	⏱️ as soon as	immediately when	⏱️ 一……就	Text me as soon as you land.	🗣️ 一到就给我发短信。
since	⏱️ since	from a past time until now or then	⏱️ 自从…至今	I have felt better since I started sleeping more.	🗣️ 自从你开始多睡觉，我感觉好多了。

Reason subordinators explain why something happens. They can sound neutral, formal, or emphatic depending on the word choice. Use them to connect a result in the main clause to a cause in the dependent clause.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
because	🧠 because	direct reason	🧠 直接原因	I left early because I felt sick.	🗣️ 我因为觉得不舒服而早早离开。
since	🧠 since	reason that is already known or background	🧠 已知或背景原因	Since you are here, let us begin.	🗣️ 既然你在这里，我们开始吧。
as	🧠 as	mild or background reason	🧠 温和或背景原因	As it was late, we went home.	🗣️ 由于很晚，我们回家了。
now that	🧠 now that	reason based on a new situation	🧠 基于新情况的原因	Now that you have finished, you can rest.	🗣️ 现在你完成了，你可以休息。

Conditional subordinators set a requirement for the main clause to be true. They can describe real possibilities, limits, or exceptions. The dependent clause expresses the condition and the main clause expresses the result.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
if	✅ if	basic condition	✅ 基本条件	If it rains, we will cancel.	🗣️ 如果下雨，我们将取消。
unless	✅ unless	negative condition meaning except if	✅ 否定条件，意思是除非	We will go unless it rains.	🗣️ 除非下雨，我们将前往。
provided that	✅ provided that	strict condition often used for rules	✅ 常用于规则的正式条件	You may leave provided that you finish your work.	🗣️ 你完成工作后可以离开。
as long as	✅ as long as	condition emphasizing duration or limits	✅ 强调持续时间或限制的条件	You can borrow it as long as you return it today.	🗣️ 只要你今天归还，你就可以借用。
even if	✅ even if	result stays the same despite the condition	✅ 条件无论如何，结果都相同	I will go even if it is snowing.	🗣️ 即使下雪，我也会去。

Concession subordinators show that the main clause is true even though the dependent clause presents a contrast. They are useful for balancing two ideas that do not align in the expected way. Choose a word that matches how strong the contrast is and how formal you want to sound.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
although	⚖️ although	contrast with a clear concession	⚖️ 具有明确让步的对比	Although I was tired, I finished the report.	🗣️ 尽管我很累，我还是完成了报告。
though	⚖️ though	similar to although, often more conversational	⚖️ 与 although 相似，通常更口语化	I liked the movie, though it was long.	🗣️ 我喜欢这部电影，虽然它很长。
even though	⚖️ even though	strong concession	⚖️ 强烈让步	Even though it was expensive, we bought it.	🗣️ 尽管它很贵，我们还是买了。
whereas	⚖️ whereas	contrast between two facts	⚖️ 两个事实之间的对比	She likes tea, whereas I prefer coffee.	🗣️ 她喜欢茶，而我更喜欢咖啡。
while	⚖️ while	contrast between two facts, also used for time	⚖️ 两个事实之间的对比，也用作时间	While the plan is simple, it is not easy.	🗣️ 计划很简单，然而并不容易。

Purpose subordinators explain the goal of an action in the main clause. They answer the question why someone does something, focusing on intention rather than cause. They are common in instructions, plans, and formal writing.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
so that	🎯 so that	with the purpose that	🎯 为了……的目的	I saved the file so that I could send it later.	🗣️ 我保存了文件，以便稍后发送。
in order that	🎯 in order that	formal version of so that	🎯 为了……的正式形式	She spoke quietly in order that the baby would not wake.	🗣️ 她小声地说话，为了不吵醒宝宝。
so	🎯 so	informal purpose, often before an adjective or phrase	🎯 非正式的目的，常放在形容词或短语前	I left early so I would not miss the train.	🗣️ 我走得很早，这样就不会错过火车。

Some subordinating conjunctions present a result that follows from the main clause. This is different from reason: the dependent clause shows the outcome, not the cause. These forms often emphasize the strength or extent of the main clause.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
so that	📈 so that	can also introduce a result, depending on meaning	📈 也可引出结果，具体含义而定	He whispered so that nobody heard him.	🗣️ 他低声说话，以便没有人听见他。
so plus adjective that	📈 so plus adjective that	result of a degree or intensity	📈 表示程度或强度的结果	The test was so hard that many students failed.	🗣️ 考试太难，导致许多学生不及格。
such plus noun that	📈 such plus noun that	result of a type or kind	📈 某种类型的结果	It was such a good meal that we ordered dessert.	🗣️ 那是一顿很好吃的饭，我们点了甜点。

Subordinating conjunctions create an unequal relationship: one clause depends on the other. Coordinating conjunctions create an equal relationship between two independent clauses. Knowing the difference helps you punctuate correctly and choose structures that match your meaning.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 例子
Subordinating conjunction plus dependent clause cannot stand alone	🔗 从属连词加从句不能单独成立	Because I was late is incomplete.	📝 因为我迟到了，这句话是不完整的。
Coordinating conjunction links two independent clauses	🔗 并列连词将两个独立从句连接	I was late, but I still came.	📝 我迟到了，但我仍然来了。
Subordination often answers a specific question about the main clause	🔗 从属通常回答关于主句的特定问题	I stayed home because I was sick answers why.	🗣️ 我呆在家里，因为我生病了。

Many subordinating conjunctions have close substitutes that differ mainly in tone. Some are more formal and common in academic or legal contexts, while others are more conversational. Choosing an appropriate conjunction helps your writing sound natural for the situation.

Word/Phrase	🇨🇳 中文 单词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 例句
because	🗂️ because	neutral, common in speech and writing	🗂️ 中性，口语与书写中都常见	I stayed because I wanted to help.	🗣️ 我留下来是因为我想帮忙。
since	🗂️ since	slightly more formal or backgrounded reason	🗂️ 稍正式或有背景的原因	Since the data is incomplete, we will wait.	🗣️ 由于数据不完整，我们将等待。
provided that	🗂️ provided that	formal and conditional, common in rules	🗂️ 正式且有条件，规则中常见	You may enter provided that you show ID.	🗣️ 你出示身份证即可进入。
though	🗂️ though	more conversational concession	🗂️ 更口语化的让步	It is expensive, though it lasts a long time.	🗣️ 尽管很贵，但它用得很久。