Perfect Tense with '了'

01

Basic Structure: Verb + 了 (le)

To show that an action has been completed, place 了 (le˙ㄌㄜlê) directly after the action verb. This structure is generally used when the object of the verb is specific (quantified or defined), such as "one apple" or "that book".

The structure is: Subject + Verb + 了 (le˙ㄌㄜlê) + (Number/Measure Word) + Object

• 我买了一本书。

  wǒ mǎi le yī běn shū.ㄨㄛˇ ㄇㄞˇ ˙ㄌㄜ ㄧ ㄅㄣˇ ㄕㄨ.wo3 mai3 lê yi1 pên3 shu1.

  I bought a book.

• 他喝了一杯水。

  tā hē le yī bēi shuǐ.ㄊㄚ ㄏㄜ ˙ㄌㄜ ㄧ ㄅㄟ ㄕㄨㄟˇ.t'a1 ho1 lê yi1 pei1 shui3.

  He drank a glass of water.

• 我们看了一个电影。

  wǒ·men kàn le yī gè diàn·yǐng.ㄨㄛˇ·˙ㄇㄣ ㄎㄢˋ ˙ㄌㄜ ㄧ ㄍㄜˋ ㄉㄧㄢˋ·ㄧㄥˇ.wo3·mên k'an4 lê yi1 ko4 tien4·ying3.

  We watched a movie.

02

Only Used with Action Verbs

The particle 了 (le˙ㄌㄜlê) is used with verbs that describe a dynamic action, such as "to eat," "to buy," or "to go."

It is generally not used with stative verbs (verbs that describe a state of being) to mark completion. You do not use 了 (le˙ㄌㄜlê) after words like 是 (shìㄕˋshih4) - to be, 在 (zàiㄗㄞˋtsai4) - to be at, 有 (yǒuㄧㄡˇyu3) - to have, or 喜欢 (xǐ·huānㄒㄧˇ·ㄏㄨㄢshi3·huan1) - to like to indicate the past tense.

• 昨天我在家。

  zuó·tiān wǒ zài jiā.ㄗㄨㄛˊ·ㄊㄧㄢ ㄨㄛˇ ㄗㄞˋ ㄐㄧㄚ.tso2·t'ien1 wo3 tsai4 chia1.

  I was at home yesterday. (Correct: no "le")

• 昨天我在家了。

  zuó·tiān wǒ zài jiā le.ㄗㄨㄛˊ·ㄊㄧㄢ ㄨㄛˇ ㄗㄞˋ ㄐㄧㄚ ˙ㄌㄜ.tso2·t'ien1 wo3 tsai4 chia1 lê.

  (Incorrect: don't use "le" for simple past state)

03

Negating Completed Actions

This is a crucial rule: When negating an action in the past (saying you did not do something), you must use 没 (méiㄇㄟˊmei2) or 没有 (méi·yǒuㄇㄟˊ·ㄧㄡˇmei2·yu3).

When you use 没 (méiㄇㄟˊmei2), you must remove the 了 (le˙ㄌㄜlê). You cannot have both 没 (méiㄇㄟˊmei2) and 了 (le˙ㄌㄜlê) in the same sentence regarding completed actions.

• 我没吃早饭。

  wǒ méi chī zǎo·fàn.ㄨㄛˇ ㄇㄟˊ ㄔ ㄗㄠˇ·ㄈㄢˋ.wo3 mei2 ch'ih1 tsao3·fan4.

  I didn't eat breakfast.

• 他没买那个东西。

  tā méi mǎi nà gè dōng·xi.ㄊㄚ ㄇㄟˊ ㄇㄞˇ ㄋㄚˋ ㄍㄜˋ ㄉㄨㄥ·˙ㄒㄧ.t'a1 mei2 mai3 na4 ko4 tung1·shi.

  He didn't buy that thing.

04

Using '了 (le)' in the Future

Because 了 (le˙ㄌㄜlê) marks completion rather than past tense, it can be used in future contexts. In these cases, it indicates that one action will be completed before another action begins. This is similar to saying "Once I have done X, I will do Y."

• 你到了给我打电话。

  nǐ dào le gěi wǒ dǎ diàn·huà.ㄋㄧˇ ㄉㄠˋ ˙ㄌㄜ ㄍㄟˇ ㄨㄛˇ ㄉㄚˇ ㄉㄧㄢˋ·ㄏㄨㄚˋ.ni3 tao4 lê kei3 wo3 ta3 tien4·hua4.

  Call me when you have arrived.

• 我吃完饭就去。

  wǒ chī wán fàn jiù qù.ㄨㄛˇ ㄔ ㄨㄢˊ ㄈㄢˋ ㄐㄧㄡˋ ㄑㄩˋ.wo3 ch'ih1 wan2 fan4 chiu4 ch'ü4.

  I will go as soon as I have finished eating.

05

Verb-le vs. Sentence-le

There are two positions for 了 (le˙ㄌㄜlê), and they have different meanings.

• After the verb (Verb-le): Indicates the action is complete (as explained above).
• At the end of the sentence (Sentence-le): Indicates a change of state or a new situation (e.g., "It is raining now" or "I have decided to go").

Sometimes a sentence can have both, or the position might change the meaning slightly.

• 我吃了一个苹果。

  wǒ chī le yī gè píng·guǒ.ㄨㄛˇ ㄔ ˙ㄌㄜ ㄧ ㄍㄜˋ ㄆㄧㄥˊ·ㄍㄨㄛˇ.wo3 ch'ih1 lê yi1 ko4 p'ing2·ko3.

  I ate an apple. (Action completed)

• 我不吃苹果了。

  wǒ bù chī píng·guǒ le.ㄨㄛˇ ㄅㄨˋ ㄔ ㄆㄧㄥˊ·ㄍㄨㄛˇ ˙ㄌㄜ.wo3 pu4 ch'ih1 p'ing2·ko3 lê.

  I don't eat apples anymore. (Change of habit/state)