Chinese Grammar: Lesson: Using 了 to indicate a complete action

了(le) is one of the most frequently used function words in modern Chinese language. By itself, it has no concrete meaning; it should be seen as a “helper” word that has different functions. Although 了 is a really short word, this tiny word leaves Lupishu feeling puzzled on how to use it and where to place it in the sentence. You too? Hold on, we’ll make 了 easier to understand in this lesson! Ready? Let’s look at this particle word 了.

Basically, the role 了 takes on depends on its place in the sentence. Here, we’re going to talk about its uses when it's placed right after the verb.

了 the completed action marker

When you want to express something or actions that have been completed, you use “了”. When 了 marks a completed action, it is always placed right after the main verb. This first basic use is one of the most common uses of 了.

Structure

Verb + 了(le)+ object

In this case, the particle 了 doesn’t have an influence on the tense, it just expresses a completed action.

A frequent mistake is to think that because 了 indicates that a verb was completed, it is close in meaning to the past tense in English. I did this, I ate that... However, a verb can be completed in all tenses, and as you’ll see in the examples, 了 as an aspect marker can be used in all tenses: in the present, past or future.

Examples

我 昨天 吃了三 个 苹果。
I ate three apples yesterday. (past)

我 走了以后，就 没 人 和 你 说话了。
There won’t be anyone to talk to after I leave. (future) / After I leave, no one will talk to you.

我 出发了。
I’ m leaving. (present)

Duration with 了

Now that you’ve established the action was completed, thanks to our friend 了, how about talking how long said action lasted? Simply add a duration after the verb followed by 了 to do so.

Structure

Subject + Verb + 了 + duration

Examples

他 学了五 年 汉语.
He studied Chinese for 5 years.

我 以前 在 上海 住了两 年。
I lived two years in Shanghai. (previously)

If you want to be even clearer about the fact this took place in the past, a time word like 以前(before) is a great addition to your sentence, like in that last sentence.

Asking about completed actions

To ask a question about a completed action, you’ll need to use both 了 and the question word 吗 (ma), at the end of your question. You’ll often see the two paired together in a 了吗 pattern. This pattern is pretty simple to learn, as you’re now a pro at asking questions with 吗, right?

Structure

Subject + Verb + Object + 了吗?

Examples

你 去了吗？
Did you go?

你 吃 过 饭了吗？
Have you eaten yet?

你 写完 作业了吗？
Are you done with your homework?

Cases where you can’t use 了

There are some cases where you can’t use 了, some are more obvious than others. Let’s see a few.

Negation

If something didn’t happen, it can’t be completed, right? 了, therefore, cannot be used in a negative situation.

Example

To say I didn't eat:
我 没 吃饭了 is wrong.
我 没 吃饭 is correct.

Habits

When talking about habits, 了 the completed action marker is unwelcome. If you’re talking about your habit, you’re talking about something you do regularly and plan on repeating, therefore it’s not really completed, right? Even if you’re talking about a past habit, is still not accepted.

Look for words expressing a regularity (常常, 每天...) or a continuity (都, 总是...) for clues as to whether or not you should be using 了.

Example

To say He used to study French every morning:
以前 他 每天 早上 都 学了法文 is wrong
以前 他 每天 早上 都 学 法文。 is correct.

Verbs that describe a state

Any verbs that describe how something IS - i.e verbs that describe a state - cannot be used with 了. A state is or isn't, there is no action going about it, so 了 cannot be used.

As such, verbs like 是 (to be), 在 (to be at) and 有 (to have) are anti 了 so don’t go offering 了’s help to these verbs if they’re the main verbs in the sentence.

Verbs in particular that express feelings or describe a mental state cannot be followed by our tiny helper friend 了. Is it because feelings are fleeting and moods subject to change? Or rather because they describe one's state and no action is required?
Here are some of the most common verbs you won’t be able to worry about adding 了 to: 应该 (to have to), 要 (to want), 想 (to want), 得 (to have to), 爱 (to love), 喜欢 (to like), 觉得 (to think, to feel), 愿意 (to be willing to), 希望, (to hope), 知道 (to know)..._

Examples

To say: I should have gone to see him yesterday
我 昨天 应该了去 看 他 is wrong
我 昨天 应该 去 看 他 is correct.

A few more cases

• Verbs expressing a possibility or an ability such as 可以 (to be able to), 能 (to be able to)... are also incompatible with 了, which makes sense, doesn't it?
• Adjectives (聪明, 年轻, 漂亮) also cannot be used with 了, as they also describe rather than be actions.

Now that you've seen this use of 了, what do you think? Do you understand? 你们 懂了吗?

The important thing to keep in mind is that 了 placed right after the verb indicates a completed action. Don't forget, actions can be completed in all tenses, so don't come to equate Verb + 了 with the past!