HSKReadyGet the appHSK 1 Completed Aspect: Using the Dynamic Particle 了 (le1)
The outline calls this 完成态. Post-verbal 了1 presents an action as realized or viewed as a bounded event in context. It is not a past-tense ending and does not by itself mean “finish every part of the task”.
我昨天买了三本书。
Correct: 了1 sits directly after the verb 买 and is followed by a quantified object (三本书) to report a completed past event.
× 我昨天没买了那本书。
For the intended non-occurrence, use 我昨天没买那本书, without the post-verbal aspect particle 了1.
Corrected example: 我昨天没买那本书。
Read the full explanation and examples
What Is the Completed Aspect with 了1?
In the HSK 1 grammar outline, the completed aspect (完成态) is expressed using the dynamic particle 了1 (动态助词“了1”). The label 了1 refers specifically to the particle 了 when it appears immediately after a verb, distinguishing it from sentence-final 了2, which is a separate syllabus item used to indicate a change of state.
Separate aspect from tense. Chinese verbs do not inflect for tense, and 了1 presents an action from a realized or bounded perspective. The exact endpoint comes from the verb phrase and context, not from 了 alone: 我看了那本书，可还没看完 means “I read some of that book, but have not finished it”. 完 explicitly adds finishing; 了 does not always do that work.
Core Sentence Patterns and Object Requirements
In the basic examples here, 了1 follows the verb and precedes its object. A quantified object such as 三本书 is a useful beginner pattern for a standalone report. It is not a universal rule that every object must be counted or specified: context and familiar verb–object combinations also matter, as in 我吃了药.
我昨天买了三本书。
Correct: 了1 sits directly after the verb 买 and is followed by a quantified object (三本书) to report a completed past event.
上午他喝了一杯咖啡。
Correct: A single bounded action completed during the morning timeframe, paired with a specific quantity (一杯).
周末我们看了两部电影。
Correct: Marks the total realized count of actions completed within the weekend period.
Notice how in each example above, the timeline is set by a time word (yesterday, this morning, the weekend), the verb is immediately followed by 了, and the object includes a number and measure word. If you also want to connect two actions in sequence—where the second action only happens after the first one is finished—you can use 了1 after the first verb, even without a number on the object, because the following clause completes the sentence.
Why Completed Aspect Is Not Past Tense
The clearest proof that 了1 does not mean past tense is how it works on a future timeline. Picture tomorrow morning: you have two planned events—eating breakfast and going to school. Going to school happens only after eating breakfast is completed. Relative to the moment you head out the door tomorrow, the breakfast action is finished.
明天我吃了早饭就去学校。
Correct: Demonstrates that 了1 is aspect, not past tense. Eating breakfast must be completed on tomorrow's timeline before going to school begins.
Here, 了1 marks the completion of the first action (eating breakfast) prior to the start of the second action (going to school). Conversely, an event in the past does not automatically take 了1 if you are describing an ongoing background state, a habitual routine, or a general feeling rather than a single bounded action.
- A past event viewed as realized: 了1 can mark that perspective, but being in the past alone does not require it.
- Future prerequisite event: Action A must finish before Action B starts (uses Verb 1 + 了1).
- A plain routine such as 他每天喝一杯咖啡 normally has no 了1. A repeated sequence can still use it: 他每天吃了饭就出门 presents eating as preceding each departure.
Key Contrasts: Habitual Actions and Negation
Comparing a single realized event with a daily habit shows why 了1 is situational. Earlier, we saw a sentence about drinking one cup of coffee this morning (with 了). Compare that with a statement about someone's everyday routine:
他每天喝一杯咖啡。
Correct contrast: Describes a general habitual routine rather than a single completed instance, so 了1 is not used.
The daily-habit sentence does not focus on a particular realized occasion, so it normally omits 了1. A habit is a generalization, not proof of exactly what happened yesterday. A repeated sequence such as 吃了饭就出门 can use 了1 without ceasing to be habitual.
Another vital rule involves negation. If an action did not take place, it was never completed. To say that an action did not happen, Chinese uses 没 (or 没有) before the verb, and you must remove 了1. Keeping 了1 after a verb negated with 没 is a classic learner error because it simultaneously claims the action was not done and that it was completed.
× 我昨天没买了那本书。
For the intended non-occurrence, use 我昨天没买那本书, without the post-verbal aspect particle 了1.
Corrected example: 我昨天没买那本书。
我昨天没买那本书。
Correct replacement for “我昨天没买了那本书。”: Negate a non-realized action with 没 before the verb and drop 了.
Frequently asked questions
What is the difference between 了1 and 了2 in the HSK 1 syllabus?
In the outline’s basic distinction, post-verbal 了1 marks the action’s realized/bounded perspective, while sentence-final 了2 marks a new situation. Do not identify their function from final position alone: in a sentence without a following object, one final 了 may also have an aspectual role.
Do I need to put 了1 in every sentence about yesterday or last year?
No. Past time alone does not determine the use of 了1. Consider whether the sentence presents a particular realized action, an ongoing situation or a routine. For ordinary negation of a non-occurring action, use 没（有） without 了1.
Why do beginners usually put a number or measure word after Verb + 了?
A number and classifier makes the amount explicit and gives beginners a clear standalone example: 我买了三本书. It is helpful, not obligatory for every object. Bare objects can work when the combination and context support them, as in 我吃了药.
