The Use of Perfective 了 (le) in Affirmative Sentences in Mandarin Chinese

In Mandarin Chinese, the particle 了 (le) plays a pivotal role in indicating that an action is perceived as complete and bounded. This grammatical feature, known as the perfective aspect, provides critical information about the nature and status of actions within a sentence. Importantly, 了 (le) is used exclusively in affirmative sentences and never in negative ones. This article explores the reasons behind this restriction and its implications for understanding and accurately using Mandarin Chinese.

Understanding the Perfective Aspect

The perfective aspect is a grammatical category used to express a completed action or event. It contrasts with the imperfective aspect, which describes actions that are ongoing, habitual, or otherwise unbounded in time. In English, for example, the distinction between “I have eaten” (perfective) and “I am eating” (imperfective) clearly illustrates this difference.

In Mandarin Chinese, the particle 了 (le) marks the perfective aspect. When appended to a verb, it signifies that the action has been completed at a specific point in time. For example:

  • 我吃了饭。(Wǒ chī le fàn.) – “I have eaten.”
  • 他到了。(Tā dào le.) – “He has arrived.”

In these sentences, 了 (le) indicates that the actions of eating and arriving are viewed as completed and bounded events, providing a clear temporal framework.

The Incompatibility of 了 (le) with Negative Sentences

The particle 了 (le) does not appear in negative sentences due to the inherent nature of negation. Negation, by definition, denies the occurrence of an action or event. Therefore, it is impossible to view a non-occurring action as complete or bounded. The following negative sentences exemplify this point:

  • 我没吃饭。(Wǒ méi chī fàn.) – “I have not eaten.”
  • 他没到。(Tā méi dào.) – “He has not arrived.”

In these instances, the negation marker 没 (méi) precludes the use of 了 (le). Since the actions of eating and arriving are negated, they are not completed events and thus cannot be marked with the perfective aspect.

Contextual Influence in Affirmative and Negative Sentences

Context significantly influences the use of 了 (le) in Mandarin Chinese. In affirmative sentences, the completion of an action can be explicitly stated or implied through the context. Consider the following example:

  • 她看了那本书。(Tā kàn le nà běn shū.) – “She has read that book.”

Here, 了 (le) explicitly indicates that the action of reading the book is complete. Conversely, in negative sentences, the occurrence of the action is denied, making it impossible to apply the perfective aspect:

  • 她没看那本书。(Tā méi kàn nà běn shū.) – “She has not read that book.”

Since the action of reading the book did not occur, there is no basis for marking it as complete or bounded.

Other Aspects of 了 (le) Usage

Apart from marking the perfective aspect, 了 (le) can also be used to indicate a change of state, often at the end of a sentence. For instance:

  • 天气变冷了。(Tiānqì biàn lěng le.) – “The weather has turned cold.”
  • 他走了。(Tā zǒu le.) – “He has left.”

In these sentences, 了 (le) signifies a transition or change, rather than merely the completion of an action.

Additionally, 了 (le) can be used in conjunction with other particles to express nuances of time and action completion. For example:

  • 我已经吃了饭了。(Wǒ yǐjīng chī le fàn le.) – “I have already eaten.”
  • 他刚刚走了。(Tā gānggāng zǒu le.) – “He just left.”

These constructions provide further layers of meaning, indicating not only that the action is complete but also adding a temporal context.

Common Mistakes and Tips for Learners

One common mistake learners make is using 了 (le) in negative sentences or incorrectly applying it in contexts where it does not belong. To avoid this, learners should practice identifying whether an action is complete and affirmed before deciding to use 了 (le).

  • Incorrect: 我没吃了饭。(Wǒ méi chī le fàn.) – “I have not eaten.” (Incorrect use of 了)
  • Correct: 我没吃饭。(Wǒ méi chī fàn.) – “I have not eaten.”

Learners should also be aware of the different contexts in which 了 (le) is used to indicate a change of state or a completed action. Understanding these distinctions helps in forming sentences that are both grammatically correct and contextually appropriate.

Implications for Mandarin Chinese Learners

For learners of Mandarin Chinese, understanding the use of 了 (le) is essential. It highlights the importance of recognizing aspectual nuances in the language and provides insight into how actions are perceived and expressed. When forming negative sentences, learners must remember to omit 了 (le) and instead use appropriate negation markers such as 没 (méi).

Additionally, mastering the use of 了 (le) enables learners to convey the correct temporal and aspectual meanings in their sentences. This understanding not only enhances grammatical accuracy but also enriches communication by allowing for precise descriptions of actions and events. For instance:

  • 他已经做完了作业。(Tā yǐjīng zuòwán le zuòyè.) – “He has already finished his homework.”

Here, 了 (le) after 做完 (zuòwán) indicates the completion of the action of finishing homework, providing a clear sense of time and aspect.

Practical Dialogues Using 了 (le)

To illustrate the use of 了 (le) in everyday conversation, consider the following dialogues:

Dialogue 1:

A: 你吃饭了吗?(Nǐ chīfàn le ma?) – “Have you eaten?” B: 我已经吃了。(Wǒ yǐjīng chī le.) – “I have already eaten.”

In this dialogue, 了 (le) in the response indicates the completion of the action of eating.

Dialogue 2:

A: 天气变冷了。(Tiānqì biàn lěng le.) – “The weather has turned cold.” B: 是啊,冬天来了。(Shì a, dōngtiān lái le.) – “Yes, winter has arrived.”

Here, 了 (le) is used to indicate a change of state, emphasizing the transition to colder weather.

Dialogue 3:

A: 你看到那部电影了吗?(Nǐ kàndào nà bù diànyǐng le ma?) – “Have you seen that movie?” B: 我还没看呢。(Wǒ hái méi kàn ne.) – “I haven’t seen it yet.”

In this dialogue, the absence of 了 (le) in the negative response highlights that the action of watching the movie has not occurred.

Advanced Grammar Points

To further deepen our understanding, let’s explore some advanced grammar points related to 了 (le).

  1. Double 了 Construction (Verb + 了 + Object + 了):This construction is used to emphasize the completion of an action and its relevance to the current situation.
    • 他吃了饭了,可以出发了。(Tā chī le fàn le, kěyǐ chūfā le.) – “He has eaten, and he can leave now.”
  2. Aspect Particle 过 (guò) vs. 了 (le):The particle 过 (guò) is used to indicate that an action has been experienced in the past, whereas 了 (le) emphasizes the completion of an action.
    • 我去过中国。(Wǒ qù guò Zhōngguó.) – “I have been to China.” (Experience)
    • 我去了中国。(Wǒ qù le Zhōngguó.) – “I went to China.” (Completion)
  3. Using 了 (le) with Modal Verbs:When 了 (le) is used with modal verbs like 能 (néng, can) and 会 (huì, will), it indicates that the action is both possible and completed.
    • 他能写完了。(Tā néng xiě wán le.) – “He is able to finish writing.”

Narration and Storytelling Using 了 (le)

In storytelling, 了 (le) plays an essential role in advancing the plot and indicating completed actions. Consider the following narrative:


(Yī tiān wǎnshàng, Xiǎomíng hé tā de péngyǒu men juédìng qù kàn diànyǐng. Dào le diànyǐngyuàn, tāmen fāxiàn diànyǐng yǐjīng kāishǐ le. Xiǎomíng shuō: “Wǒmen lái wǎn le!” Tāmen jímáng zhǎo le zuòwèi, kāishǐ kàn diànyǐng. Diànyǐng jiéshù hòu, Xiǎomíng shuō: “Zhè bù diànyǐng zhēn hǎokàn!” Péngyǒu men yě dōu diǎn le diǎntóu, tóngyì tā de kànfǎ.)

In this short story:

  • “到了电影院” (dào le diànyǐngyuàn) – “Arrived at the cinema,” indicates the action of arriving is complete.
  • “电影已经开始了” (diànyǐng yǐjīng kāishǐ le) – “The movie has already started,” shows the action of starting is complete.
  • “我们来晚了” (wǒmen lái wǎn le) – “We are late,” uses 了 (le) to emphasize the completed state of being late.
  • “他们急忙找了座位” (tāmen jímáng zhǎo le zuòwèi) – “They hurriedly found seats,” shows the completion of the action of finding seats.
  • “朋友们也都点了点头” (péngyǒu men yě dōu diǎn le diǎntóu) – “The friends also nodded,” indicating the completed action of nodding in agreement.

This narrative demonstrates how 了 (le) is used to indicate completed actions, making the story more dynamic and clear.

Exercises for Practice

To reinforce the understanding of 了 (le), here are some exercises:

  1. Complete the sentences with the correct use of 了 (le):
    • 我___吃___饭了。(Wǒ ___ chī ___ fàn le.) – “I have eaten.”
    • 天气___冷了。(Tiānqì ___ lěng le.) – “The weather has turned cold.”
    • 他___到___家了。(Tā ___ dào ___ jiā le.) – “He has arrived home.”
  2. Rewrite the sentences in negative form without using 了 (le):
    • 他吃了饭。(Tā chī le fàn.) – “He has eaten.”
    • 他们去了公园。(Tāmen qù le gōngyuán.) – “They went to the park.”
  3. Translate the following sentences into Chinese, using 了 (le) appropriately:
    • “I have already finished my homework.”
    • “She has just left the office.”
    • “The weather has changed.”

Vocabulary List

  • 吃 (chī) – to eat
  • 饭 (fàn) – meal, rice
  • 到 (dào) – to arrive
  • 天气 (tiānqì) – weather
  • 变冷 (biàn lěng) – to turn cold
  • 走 (zǒu) – to leave, to walk
  • 电影院 (diànyǐngyuàn) – cinema
  • 开始 (kāishǐ) – to start
  • 座位 (zuòwèi) – seat
  • 电影 (diànyǐng) – movie
  • 结束 (jiéshù) – to end
  • 好看 (hǎokàn) – good-looking, nice
  • 同意 (tóngyì) – to agree
  • 做完 (zuòwán) – to finish
  • 作业 (zuòyè) – homework
  • 朋友 (péngyǒu) – friend


The perfective particle 了 (le) is a powerful grammatical tool in Mandarin Chinese, enabling speakers to indicate the completion and boundedness of actions. Its exclusive use in affirmative sentences underscores the intrinsic link between the perfective aspect and the concept of completed actions. By recognizing that 了 (le) cannot appear in negative sentences, learners and speakers of Mandarin can better grasp the intricacies of the language and improve their communicative competence. This understanding aids in forming grammatically correct sentences and deepens one’s appreciation of the language’s structure and expressive capabilities, ultimately leading to more effective and nuanced communication in Mandarin Chinese. Mastery of 了 (le) is a crucial step toward fluency, allowing learners to convey precise meanings and temporal contexts in their speech and writing.

Sign up for a free trial class here.

Sign up for classes here.

Learn more about our Chinese Summer Camp for Children here.

Learn about our Internship Program in China.

Get free Chinese learning resources.

Learn about China’s 2024 Offical Holiday Schedule

Ønsker du en gratis prøveklasse? Registrer deg!

Bli med på en gratis prøveklasse i kinesisk!

Do you want a Free Trial Chinese Class? Register now!

Join a Free Trial Chinese Class!