Time Clauses: 在…以前/以后, 当…的时候

Q: How do you use 时间状语 (Time Clauses) in a sentence?

在睡觉以前，他喜欢看书。 — Zài shuì jiào yǐ qián, tā xǐ huān kàn shū. — Before going to sleep, he likes to read. 在 + VP + 以前 = time clause before an action; main clause follows.

Chinese grammar · HSK 2 · 时间状语 · By Carson 木林森 · Updated October 2026

A time clause sets the moment of the main action by anchoring it to another event. This page covers 在…以前 (before), 在…以后 (after) and 当…的时候 (when), with the clause going first.

在 zài to exist; to be alive 以前 yǐ qián 以后 yǐ hòu 当 dāng (onom.) dong 的时候 de shí hòu

Pattern 2: 当…的时候 — at the time when…
- 当我很小的时候，住在北京。(When I was very young, I lived in Beijing.)
- Use 当 for simultaneous background situations.

❌ 以前吃饭，请洗手。(wrong — 以前 must come after the time noun/VP)
✅ 吃饭以前，请洗手。(correct simplified form without 在)

Worked examples

Chinese	Pinyin	English	What it shows
在睡觉以前，他喜欢看书。	Zài shuì jiào yǐ qián, tā xǐ huān kàn shū.	Before going to sleep, he likes to read.	在 + VP + 以前 = time clause before an action; main clause follows
下课以后，我们一起去吃饭，好吗？	Xià kè yǐ hòu, wǒ men yī qǐ qù chī fàn, hǎo ma?	After class, let's go eat together, OK?	VP + 以后 at start of sentence; main clause with proposal follows
当我们在学校的时候，老师给了我们很多作业。	Dāng wǒ men zài xué xiào de shí hòu, lǎo shī gěi le wǒ men hěn duō zuò yè.	When we were at school, the teacher gave us a lot of homework.	当…的时候 frames simultaneous background situation for main event

Word by word

Each word in this pattern on its own: what it does here, the structure, three more examples, and the mistake to avoid.

以前 (yǐ qián)

Means 'before' and comes after the clause.

Structure: Clause + 以前, main clause

Chinese	Pinyin	English
吃饭以前，请先洗手。	Chī fàn yǐ qián, qǐng xiān xǐ shǒu.	Before eating, please wash your hands first.
来中国以前，我没吃过饺子。	Lái zhōng guó yǐ qián, wǒ méi chī guò jiǎo zi.	Before I came to China I had never eaten dumplings.
他十年以前住在上海。	Tā shí nián yǐ qián zhù zài shàng hǎi.	He lived in Shanghai ten years ago.

Not: ~~以前我去学校，我吃了早饭。~~ With a verb clause, 以前 comes after it: 我去学校以前，我吃了早饭.

以后 (yǐ hòu)

Means 'after' and comes after the clause.

Structure: Clause + 以后, main clause

Chinese	Pinyin	English
毕业以后，他想去中国工作。	Bì yè yǐ hòu, tā xiǎng qù zhōng guó gōng zuò.	After graduating, he wants to work in China.
三年以后，我的汉语会更好。	Sān nián yǐ hòu, wǒ de hàn yǔ huì gèng hǎo.	In three years my Chinese will be better.
吃了药以后，我觉得好多了。	Chī le yào yǐ hòu, wǒ jué de hǎo duō le.	After taking the medicine, I felt much better.

Not: ~~我吃饭以后了去学校。~~ Do not put 了 after 以后: 我吃了饭以后去学校.

In the official HSK 3.0 grammar outline: level 3, fixed patterns.

的时候 (de shí hou)

Means 'when' and closes the clause.

Structure: Clause + 的时候, main clause

Chinese	Pinyin	English
小的时候，我住在农村。	Xiǎo de shí hou, wǒ zhù zài nóng cūn.	When I was little, I lived in the countryside.
吃饭的时候，别看手机。	Chī fàn de shí hou, bié kàn shǒu jī.	Do not look at your phone while eating.
我在北京的时候，常去爬山。	Wǒ zài běi jīng de shí hou, cháng qù pá shān.	When I was in Beijing, I often went hiking.

Not: ~~的时候我在北京，常去爬山。~~ 的时候 closes the clause; it does not lead it: 我在北京的时候, 常去爬山.

当…的时候 (dāng…de shí hou)

Gives a more formal 'at the time when'.

Structure: 当 + clause + 的时候

Chinese	Pinyin	English
当你需要帮助的时候，可以给我打电话。	Dāng nǐ xū yào bāng zhù de shí hou, kě yǐ gěi wǒ dǎ diàn huà.	When you need help, call me.
当他说话的时候，大家都很安静。	Dāng tā shuō huà de shí hou, dà jiā dōu hěn ān jìng.	When he speaks, everyone is quiet.
当我听到这个消息的时候，我非常高兴。	Dāng wǒ tīng dào zhè gè xiāo xi de shí hou, wǒ fēi cháng gāo xìng.	When I heard this news, I was very happy.

Not: ~~当我是学生，我住在宿舍。~~ 当 needs 的时候 to close it: 当我是学生的时候.

Produce this pattern without stopping to think about it. GraphChinese drills Time Clauses across 12 exercises and schedules the review that keeps it.

What you need first

Every topic in GraphChinese names its own prerequisites, and these are the grammar points this one is built on. If a sentence here will not parse, one of them is why.

Time Expressions as Adverbials

Questions about Time Clauses

What does 时间状语 (Time Clauses) mean in Chinese?

A time clause sets the moment of the main action by anchoring it to another event. This page covers 在…以前 (before), 在…以后 (after) and 当…的时候 (when), with the clause going first. It is an HSK 2 grammar point.

How do you use 时间状语 (Time Clauses) in a sentence?

在睡觉以前，他喜欢看书。 — Zài shuì jiào yǐ qián, tā xǐ huān kàn shū. — Before going to sleep, he likes to read. 在 + VP + 以前 = time clause before an action; main clause follows.

What do you need to know before 时间状语 (Time Clauses)?

Time Expressions as Adverbials (HSK 1). This pattern is built out of them, so a sentence here that will not parse usually means one of them has not landed yet.

Can I drop 当 from 当…的时候?

Yes. 当 is optional, so 我到家的时候 means the same as 当我到家的时候. 当 only makes the sentence a little more formal.

Where does 在 fit in 在…以前?

在 is optional and is used with a time or a clause, as in 在睡觉以前. In speech people usually drop it and say 睡觉以前.

Time Clauses is one topic of 829. GraphChinese teaches them in prerequisite order, so this pattern reaches you on the day everything it rests on is proven. The whole course, HSK 0 through HSK 6, is $49 once for lifetime access.

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