The Particle 了 (le): Completed Actions and Changes of State

了 (le) is one of the most common and most misunderstood words in Mandarin. Many textbooks call it a "past tense marker", but that isn't quite right: Chinese verbs have no tense at all, and 了 marks something more subtle.

The core idea

了 signals that an action is completed or that a situation has changed. Whether that happened in the past is usually clear from context.

After the verb: completion

Placed right after a verb, 了 shows the action is complete:

• 我买了一本书。 (Wǒ mǎi le yì běn shū.) — I bought a book.
• 他吃了三个包子。 (Tā chī le sān ge bāozi.) — He ate three buns.

Note the specific quantity ("a book", "three buns"). When the object is a bare noun, 了 often goes at the end instead.

At the end of the sentence: change of state

At the end of a sentence, 了 shows something has become true or is now true:

• 下雨了。 (Xià yǔ le.) — It's raining (now); it has started to rain.
• 我饿了。 (Wǒ è le.) — I'm hungry (now).
• 春天到了。 (Chūntiān dào le.) — Spring has arrived.

Both together

You can use both when you want to say something was completed and that the situation now holds:

• 我吃了饭了。 (Wǒ chī le fàn le.) — I have eaten (already).

More often, speakers use a single 了 at the end: 我吃饭了。

Not every past event takes 了

Habitual past actions and states don't need it:

• 我小时候住在上海。 (Wǒ xiǎoshíhou zhù zài Shànghǎi.) — I lived in Shanghai as a child.
• 昨天很冷。 (Zuótiān hěn lěng.) — Yesterday was cold.

Future events can take 了 too

If a completed action is imagined in the future, 了 works too:

• 明天我吃了饭就去。 (Míngtiān wǒ chī le fàn jiù qù.) — Tomorrow I'll go once I've eaten.

Negation

To say something hasn't happened, use 没(有) and drop 了:

• 我没买书。 (Wǒ méi mǎi shū.) — I didn't buy the book.
• 他没吃饭。 (Tā méi chī fàn.) — He hasn't eaten.

Other uses

• 太好了！ (Tài hǎo le!) — Great!
• 好了。 (Hǎo le.) — OK, that's done / enough.
• 别说了。 (Bié shuō le.) — Stop talking.

Common mistakes

• Adding 了 to every past sentence.
• Using 了 with 没.
• Forgetting the sentence-final 了 for changed situations.

Practice

1. Describe your day using 了 for each completed action.
2. Add sentence-final 了 to state changes: tired, cold, late.
3. Turn each into a negative with 没.
4. Look up example sentences in a dictionary.

Look up words and usage with English Chinese Dictionary →