The 了 Particle: Completed Actions
动态助词：了
Mark completed actions with 了
了 placed after a verb indicates that the action has been completed. This is the verb-了, marking realization or completion of an action.
This lesson covers verb-了 (action completion). Sentence-final 了 (change of state / new situation) is a separate grammar point covered in GP 22.
Lesson Targets
Podcast
Podcast: The 了 Particle: Completed Actions (动态助词：了)
Listen to Jason & Amy explain the 动态助词：了 pattern
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Understanding 动态助词：了
Chinese doesn't have tenses like English. Instead, it uses particles to mark aspect — whether an action is completed, ongoing, or experienced. 了 (le) after a verb is the completion marker. It tells the listener: "this action is done." It's not exactly "past tense" because you can use it for future completed actions too (明天到了北京就给你打电话 — once I arrive in Beijing tomorrow, I'll call you). Think of 了 as a checkmark on the verb. This is one of the most important — and trickiest — particles in all of Chinese. English speakers instinctively want to treat 了 as a past tense marker, but it's better to think of it as a "done" marker. The action it marks could have been done five minutes ago, five years ago, or even five hours from now (in a future plan). What matters is that the action reaches completion.
Key Points
- Verb + 了 = the action has been completed: 他买了一本书 (He bought a book).
- When there's an object, it usually needs a specifier (number + measure word, or 这/那): 吃了三个苹果, not just 吃了苹果.
- To negate a completed action, use 没(有) and drop the 了: 他没买书 (He didn't buy a book).
- 了 marks completion, not past tense. It can appear in future contexts too.
- Verb-了 often appears with specific quantities: 看了两个电影 (watched two movies).
- After verb-了 + object, the sentence often continues: 我吃了饭就去 (After I eat, I'll go). The 了 marks completion of the first action before the next one.
- If the object is unspecified or bare, the sentence can sound incomplete. Adding a number, 一些, or a sentence-final particle fixes this.
- Questions about completed actions use V + 了 + 吗 or V + 没 + V: 你吃了吗？ or 你吃没吃？
Chinese thinking about time is fundamentally different from English. Rather than putting actions on a fixed timeline (past/present/future), Chinese focuses on the nature of the action itself — is it complete? Ongoing? Experienced? This is why 了 is called an "aspect marker," not a "tense marker."
Key Vocabulary
Example Sentences
他买了一本书。
He bought a book.
我写了两个汉字。
I wrote two Chinese characters.
她吃了一碗面。
She ate a bowl of noodles.
你看了那个电影吗？
Did you watch that movie?
Asking about a completed action
我没买书。
I didn't buy a book.
Negation: drop 了, use 没
他喝了三杯咖啡。
He drank three cups of coffee.
医生给我开了一些药。
The doctor prescribed me some medicine.
At the doctor — a completed action with a result
我在网上订了两张票。
I booked two tickets online.
Traveling — booking is complete
你吃了吗？
Have you eaten?
One of the most common daily greetings in Chinese
我学了半年中文了。
I've been studying Chinese for half a year now.
Double 了 — completed duration that continues to the present
Common Mistakes
When you negate with 没(有), you must drop 了. They cannot coexist.
After verb-了, a bare noun object sounds incomplete. Add a number + measure word or demonstrative to make it specific.
了 must come directly after the verb, not before it.
Practice Exercises
Tips & Tricks
Remember: 了 is a checkmark, not a clock. It marks completion, not past tense specifically.
Negation kills 了. Use 没 and drop the 了 — they're mutually exclusive.
When using verb-了, try to specify how much or how many. "I ate" is vague; "I ate three dumplings" (吃了三个饺子) is complete.
The phrase 你吃了吗？(Have you eaten?) is used so often as a greeting that it practically means "How are you?" — answering it literally is fine, but know it's also a sign of warmth.
Pro tip: when 了 appears twice in a sentence (verb-了 and sentence-final 了), it often means "an action has been going on for a while and is still continuing": 我学了两年中文了 (I've been studying Chinese for two years now).
Homework
Write about what you did yesterday. Use verb-了 in at least six sentences, and include one negative sentence with 没. Example: 我昨天看了一个电影。我没做作业。