I am confused about the 了 in the sentence:


Zhèɡe biǎo kuàile wǔ fēnzhōnɡ.

This watch is running five minutes faster.

Clearly there is no change of state. Is it for completion? I don't understand what is completed...

  • Now I'm thinking it could indeed imply a change of state: the watch initially was "running fine", but then changed to "running five minutes faster". – Puco4 Jun 26 at 23:26
  • To me, many 了 are just expletives, not actually needed and not adding any information or meaning to the sentence. I can't tell the difference between 这个表快了五分钟 and 这个表快五分钟. – joehua Jun 27 at 14:48
  • The OP's confusion just like me as to the English present tense and present perfect tense. You could just think this sentence without 了 is the present, and with 了 is present perfect. 题主的困惑就像我对之于英语的一般现在时和现在完成时一样(有时搞不清楚区别)。就这句而言,你就把没"了"的当成一般现在时,有"了"的当成现在完成时,就行了。 – Zhang Jul 2 at 2:59

It is a well-known fact in Chinese linguistics that adjectives denoting gradable attributes must be “initiated” with a certain value of degree when used in predicative constructions. In this case, we have a certain form of comparison, kind of “quite/rather X”. For example:

  1. 她很瘦 。She is (rather) slim. ??她瘦
  2. 这辆车很快。 This car is (rather) fast. ??这辆车快
  3. 这个女孩真漂亮。 This girl is really pretty. ??这个女孩漂亮

Usually, the adverb很 is used to indicate a default positive value of degree.

When the verbal suffix了 is used in a predicative construction with this kind adjectives, we also have a certain form of comparison, kind of “getting more X”. For example:

  1. 她瘦了。She is getting slimmer.
  2. 你的手表快了一点点。Your watch is getting a bit faster.
  3. 你的孩子高了。Your kid is getting taller.
  4. 几个月没见她,她好像漂亮了很多。I haven’t seen her for a couple of months. She looks much prettier.

In this case, the verbal suffix了also indicates a positive value of degree, which comes with an aspectual dimension (i.e. “getting” more X).

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  • @KKTse. So, in answer to OP's question, the suffix了 in this particular case / context is not to indicate a "completed action", but to indicate "a positive, (change in), value of degree", i.e. the watch is just "getting more" fast? – Wayne Cheah Jun 27 at 4:15
  • This might be a better way to understand the usage of 了 for English speakers. – dan Jun 27 at 4:32
  • Let me give an example to explain why people think [adjective + 了] is a thing: 紅 can be noun or adjective , but with the aspect marker了, '紅了' (became red) acting like a verb -- '紅了' = (變)紅了 . Since the verb 變 is strongly implied, it is often omitted, and that created an impression that 了 can be added not only after a verb, but it can also added after an adjective. The truth is, '了' in '紅了' is still a verb particle that serves as a result complement of the implied verb '變' – Tang Ho Jun 27 at 8:00
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    @dan I am convinced the dictionary is not wrong to state 了 can be an adverb for adjective ( But 了 as an verb particle that act as a result complement of an implied verb is still a legitimate way to use it) , edited my answer – Tang Ho Jun 27 at 9:01
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    @KK_Tse I'd say 荔枝红了很久了 and 荔枝熟了很久了. Without the last 了, the sentence sounds incomplete. And 我吃饱饭很久了 sounds stilted. we usually say 我早就吃饱了 for this context. – dan Jun 27 at 10:24

Grammatically, the completion is not only for verbs but also for adjectives. In your example 快了, 快 is an adj. Another example might be easier to understand. 苹果红了, apples turned red. 苹果熟了 is a similar example.

Here is the dictionary definition about this usage of 了.

了 / le /


(用在动词形容词后, 表示动作或变化已经完成):

read twice;


Apples got red.


And the official 新华字典 has the similar definition:


  1. 放在动词或形容词后,表示动作变化已经完成: 买~一本书 | 水位低~一米。
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  • 苹果(转)红了 - the verb 转 (turn) is implied; 苹果(成)熟了 - 成熟/ 熟 (ripen) is a verb, – Tang Ho Jun 26 at 22:22
  • Another example, 飽 is an adjective in 我很飽 (I am full); But it is a verb in 我(吃)飽了, with 吃 implied – Tang Ho Jun 26 at 22:28
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    @TangHo According to my dictionary, 熟 or 成熟 is indicated as an adjective. 苹果红了 doesn't necessarily mean 苹果转红了. In fact, when we say 苹果红了,we don't really care about the action but just the current state. – dan Jun 26 at 23:51
  • ok. I shouldn't say "成熟/ 熟 (ripen) is a verb" ; I meant when there's a 了 after the adjective, a verb is implied. e.g. 苹果(长)熟了, 苹果(转)红了, 我(吃)飽了. if we only care about the current state, we would say 苹果红, 青豆绿 – Tang Ho Jun 27 at 0:08
  • 他很聪明 = he is smart ; 他聪明了 = 他(变)聪明了 = he has became smart – Tang Ho Jun 27 at 0:14

Edit 2:

From my expert friend:

Adjectives behave very much like verbs in Chinese grammar. Like verbs, many adjectives can take aspect markers (瘦咗, 靚過), resultative particles (開心翻, 污糟晒), objects (好熟佢, 緊張啲仔女, 嬲爆佢啲同學). That’s why some grammarians call those adjectives as adjectival verbs. But they are still adjectives, and do not imply any omission of verbs before them. We think of a possible omission only because of the English grammar in the English translation (e.g. become, turn).

快了 in 这个表快了五分钟 is apparently an "adjectival verb" (adjectival + aspect marker). It is an adjective, but acts like a verb



After some consideration, I decided treating [adjective +了 ] the same as [(implied verb) + adjective + 了] . is one way to see it, but 了 does work with adjective, not as a verb particle but as an adverb 快= fast; 快了 = got faster.

"这个表[快了]五分钟" = "This watch [got faster] by five minutes "

Above is the answer with the assumption of 了 is an adverb for the adjective

Below is the answer with the assumption of 了 is a verb particle for an implied verb

Is it for completion.

手錶快了 can mean '手錶走快了' or '手錶被調快(調早)了'

If the watch is running faster than the normal speed:

  • (走快)五分钟 = (run) five minutes (faster) -- No indication of the verb (走快) is a completed action. e.g. 一小時後手錶會走快五分钟 (走快 is not a completed action here)

  • (走快了)五分钟 = (have ran) five minutes (faster) -- 了 indicates the verb (走快) is a completed action

If the watch is running at normal speed, but is five minutes ahead of the real time, it must had been set wrong:

  • (被調快)五分钟 = (be set) five minutes (ahead) -- No indication of the verb (調快) is a completed action. e.g. 明天把手錶調快五分钟 (調快 is not completed action here)

  • (被調快了) 五分钟 = (had been set) five minutes (ahead) -- 了 indicates the verb (調快) is a completed action.

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  • If the clock runs 5 minutes faster now, it will continue to do so in the future. How can this be a completed action? – Puco4 Jun 26 at 19:51
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    The clock had finished running faster for 5 minutes. If it keep running faster than normal, it might be ten minutes faster in an hour. So, "run faster for 5 minutes" is completed – Tang Ho Jun 26 at 19:58
  • I thought the sentence meant the clock is 5 minutes ahead of time, but just running at a normal speed, so then it would continue to do so. But if it means running at a faster speed, I understand it. Thank you! – Puco4 Jun 26 at 20:07
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    What's the difference between 这个表快了五分钟 and 这个表快五分钟? To me, there is no difference. – joehua Jun 27 at 14:44
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    @joehua for me, the difference is that you wouldn't use 了 in the situation where the watch is 5 minutes faster by design. – Gigablah Jun 27 at 15:55


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