义项
动态助词,用在动词后,表示动作完成
Placed directly after the verb, 了 says the action was carried through: 我买了三个苹果. It marks completion, not past time — 明天我吃了饭就去 is about tomorrow.
particle语气助词,用在句末,表示情况变化
particleAt the end of a sentence 了 announces that something has changed: 下雨了 "it’s started raining", 我十八岁了 "I’ve turned eighteen".
例句
- 我买了三个苹果。我買了三個蘋果。Wǒ (third tone, dipping) mǎile (third tone, dipping) sān (first tone, high and level) ge (neutral tone) píngguǒ. (second tone, rising)···
I bought three apples.
- 下雨了,我们不去了。下雨了,我們不去了。Xià (fourth tone, falling) yǔ (third tone, dipping) le, (neutral tone) wǒmen (third tone, dipping) bú (second tone, rising) qù (fourth tone, falling) le. (neutral tone)···
It’s raining — we’re not going after all.
常见错误
不太对昨天我去了学校了。
正确昨天我去了学校。
One 了 is enough. The verb-final 了 already reports the completed action; adding a sentence-final 了 as well suggests a change of situation you did not mean.
不太对我昨天很忙了。
正确我昨天很忙。
A past state does not take 了. Adjective + 了 means the state has just come about, which is why 我很忙了 sounds like "I’ve got busy now".