The single most common 了 error among English speakers is over-use: hearing "past" in English and stamping 了 onto every Chinese sentence that describes something earlier. But 了 is not a past-tense marker — it marks a completed, bounded change or event. That definition immediately rules out whole categories of sentence. If there is no discrete event with an endpoint — because you're describing a state, reporting a habit, or saying something didn't happen — then 了 has nothing to attach to, and adding it is wrong or changes the meaning. This page maps the no-了 zones so your past-tense stories don't come out as 了 confetti.
Habits and repeated actions take no 了
A habit is not a single bounded event — it's an open-ended pattern. There's no completion point to mark, so no 了. The time or frequency word (每天, 常常, 以前) carries the sentence.
我每天跑步。
wǒ měitiān pǎobù
I run every day. (neutral) — a habit; no completed event, no 了.
我们每周开两次会。
wǒmen měi zhōu kāi liǎng cì huì
We hold two meetings a week. (neutral) — repeated, so no 了.
小时候，妈妈常常给我讲故事。
xiǎoshíhou, māma chángcháng gěi wǒ jiǎng gùshi
When I was little, Mom often told me stories. (warm) — habitual past; 常常 carries it, no 了.
States and descriptions take no 了
"Was/were" sentences — what something was like, ongoing background conditions — describe a state, not an event. Adjective-predicate sentences (with 很, 非常…) especially resist 了. See talking about the past for the fuller picture.
那时候他很高兴。
nà shíhou tā hěn gāoxìng
He was very happy back then. (neutral) — a description of a state; no 了.
我小时候很瘦。
wǒ xiǎoshíhou hěn shòu
I was thin as a child. (neutral) — a 'was' state; no 了.
Stative and mental verbs take no 了
Verbs of being, knowing, feeling, and liking name ongoing states of mind, not bounded actions. 是, 在, 有, 知道, 认识, 喜欢, 想, 觉得, 希望 — none of these normally takes 了.
| Verb | Correct (no 了) | Meaning |
|---|---|---|
| 喜欢 | 我喜欢他。 | I like him. |
| 是 | 他以前是老师。 | He used to be a teacher. |
| 知道 | 我知道这件事。 | I know about this. |
| 觉得 | 我觉得不太对。 | I feel it's not quite right. |
我喜欢他，可是我没告诉他。
wǒ xǐhuan tā, kěshì wǒ méi gàosu tā
I like him, but I didn't tell him. (informal) — 喜欢 takes no 了; the action 告诉 is negated, also no 了.
我早就知道这件事。
wǒ zǎo jiù zhīdào zhè jiàn shì
I knew about this ages ago. (informal) — 知道 is a state; no 了 even though it's 'past'.
Negated verbs take no 了
When you say something didn't happen with 没(有), the action never occurred — so there's no completion to mark. 没 and 了 never co-occur. This is important enough to have its own page.
昨天我没去上班。
zuótiān wǒ méi qù shàngbān
I didn't go to work yesterday. (neutral) — 没 negates the event; no 了.
But 了₂ (change of state) is a different animal
Careful: several of the verbs above can take a sentence-final 了 — but then it's the change-of-state 了₂, and the meaning shifts. This is not the perfective 了₁; it announces that a new situation has come about.
我知道了。
wǒ zhīdào le
Ah, now I get it / got it. (informal) — 了₂ marks the change from not-knowing to knowing.
下雨了，我们别去了。
xià yǔ le, wǒmen bié qù le
It's started raining — let's not go. (informal) — 了₂ reports a new state, twice.
And the 了 in 太…了 ("too / so…") is yet another creature — an intensifier that has nothing to do with completion. 太贵了 (too expensive) is a state, not an event; the 了 there is obligatory because of 太, not because anything finished. Don't let it fool you into thinking states take perfective 了.
这件衣服太贵了，我买不起。
zhè jiàn yīfu tài guì le, wǒ mǎi bu qǐ
This piece of clothing is too expensive, I can't afford it. (informal) — 太…了 is an intensifier, not the perfective 了.
Common Mistakes
1. Adding 了 to a state to translate "was." For a description, drop the 了. (With 了 the sentence flips to "got tired" — a change, not a state.)
❌ 我昨天很累了。
Odd for 'I was tired yesterday' — 累了 reads as 'got tired (now)', clashing with 昨天.
✅ 我昨天很累。
wǒ zuótiān hěn lèi
I was tired yesterday. (neutral) — a state, no 了.
2. Putting 了 on a mental verb. 喜欢, 想, 觉得, 知道 name states; 了 doesn't belong.
❌ 我以前喜欢了他。
Incorrect — 喜欢 is a state verb; use 我以前喜欢他.
✅ 我以前喜欢他。
wǒ yǐqián xǐhuan tā
I used to like him. (neutral)
3. Keeping 了 on a negated verb. 没 already conveys non-completion; 了 is redundant and wrong.
❌ 他没来了。
Incorrect — 没 and 了 can't co-occur; say 他没来.
✅ 他没来。
tā méi lái
He didn't come. (neutral)
4. Marking a habit as completed. For "I run every day," no 了. (With 了 it becomes "I've taken up running" — a change, not the habit itself.)
❌ 我每天跑步了。
Wrong for a plain habit — this reads as 'I've now started running daily'.
✅ 我每天跑步。
wǒ měitiān pǎobù
I run every day. (neutral)
Key Takeaways
- 了 marks a completed, bounded event or change — not "past." No event, no 了.
- No-了 zones: habits (每天跑步), states and "was/were" descriptions (那时候他很高兴), stative/mental verbs (喜欢, 知道, 是, 觉得), and negated verbs (没去).
- 没 and 了 never co-occur.
- A sentence-final 了 on these verbs is the change-of-state 了₂ (我知道了 = "now I get it"), a different meaning — not the perfective 了.
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- Negating 了: Use 没, Drop 了HSK 2 — To say a completed action didn't happen, negate with 没(有) AND delete 了: 我吃了饭 → 我没吃饭. 没 already means 'it didn't occur', so 了 has no job left. And use 没, never 不, for past events.
- How to Talk About the Past Without TenseHSK 2 — With no past tense, Chinese conveys 'past' through time words (昨天), 了 for completion and 过 for experience — but many past sentences, especially states and habits, take no marker at all.
- The Perfective 了 (le₁): Completed ActionHSK 1 — The verb-suffix 了 (le₁) sits right after the verb and marks the action as completed or realized — 我吃了饭, 买了三本书. It is completion aspect, not past tense, so it can even point to the future: 下了课就走.