In class, we learned this sentence:

Tā shuìjiào de shíhòu. Tāde péngyǒu zhèngzài shàngwǎng.

My question is about the following three variants. For the first, we add in a 在 (zài):


For the second we omit the 的 (de):


And for the third we add in a 在 (zài) and omit the 的 (de):


Question: Which of these are grammatically correct and do they all have the same meaning?

I feel the first variant is correct, YouDao.com gives an example "当她在睡觉的时候笑了..." which seems similar (but the 在 might be part of a different grammar construct here: 在[x]笑了). The latter two examples might be wrong as most examples I've found include the 的, but I'm not sure, as I found "...但在睡觉时候..." on YouDao.com.

  • either 她在睡觉的时候 or 她在睡觉时 or 她睡觉的时候 or 她睡觉时 is acceptable, but 她睡觉时候 and 她在睡觉时候 are not.
    – xenophōn
    Commented May 24, 2019 at 1:42

5 Answers 5

  • Grammatically correct:



To me, they have basically the same meaning. There are two 在 in the second sentence, and that feels kind of like a redundancy. I more often omit the first 在, especially when speaking.

  • Grammatically wrong:



If you want to use "something ... 时候", you will use "something ... 的時候". You cannot omit the 的. Or if you really want to omit the 的, you should use "something ... 时", instead of "something ... 时候".

i.e. "她睡觉时,她的朋友正在上网。" and "她在睡觉时,她的朋友正在上网。" are correct. And again, "她睡觉时" sounds more natural to me, but both are grammatically correct.

  1. 她在睡觉的时候,她的朋友正在上网。

  2. 她睡觉时候,她的朋友正在上网。


The first one is the most natural way to say it, grammatically and formally.

The second one is ok in colloquial contexts with omitting both 在 and 的.

The third one is a bit odd because it adds 在, I may expect the interlocutor to say the full version. Otherwise, I expect they say the shorten version like the second one.

But, in practice, especially when you speak fast, it really doesn't matter. These sentences are all ok, though the first one is preferable. There are no problems for understanding. They all could sound natural if you have a good command of Chinese speaking.


她在睡觉的时候 is the most completed one.

她睡觉的时候 is OK

她睡觉时候 and 她在睡觉时候 are wrong.

But these are also correct:

他在睡觉时 他睡觉时


Grammatically different.

...的时候 or ...之时means the time when ..., it's a noun with an attributive clause. This structure is just like 喝水的人(normal tense) 正在跳动的球(present tense) .

在...的时候or 在...之时 means when ..., it's an adverbial clause

You can say 利用空闲的时候来读书, but 利用在空闲的时候来读书 is wrong.

The last two examples are completely wrong grammar.


Conclusion is 在 may be omitted without problems, but if you want to omit 的, you’d better omit 候 at the same time.

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