Under what circumstances can police use tear gas?

I translate it as


Someone told me this is not correct because it shouldn't end with 吗. But I don't understand, if can police use tear gas can be translated as 警察可以使用电击枪吗? then why can't the given example?

Should the statement "Under what circumstances", when featured in a question, also include 吗 ?


4 Answers 4


“吗” is used in "Yes-no questions", which are question that can be answered by "yes" or "no".

With "Under what circumstances"/"在什么情况下", the question cannot be answered by "yes" nor "no". So "吗" should not be used.

  • If I had seen your answer earlier, I wouldn't have written mine. :) +1
    – dan
    Jun 30, 2020 at 10:51

Basically, 吗 is a yes-or-no question.

Under what circumstances can police use tear gas?

Apparently, this question can not be answered by yes or no. The answer should be something like under xxx circumstance, the police can use it.

Can police use tear gas?

This is a yes or no question. You can simply answer it with: "Yes, they can".

This might be an easy way to distinct.

Hope it could help.


The whole of "'在什么情况下..." is already encapsulated in "吗?", and so it is redundant.

In other words, the 吗? in 警察可以使用电击枪吗? replaces 在什么情况下....?


When you say 'make a question', do you mean in a written or spoken form?

I would say that the sentence that you have provided seems to be grammatically correct, although often you would probably put the subject at the beginning of the sentence (or omit it if the subject is implied or obvious)


In written form it is preferable to put 吗 and ?at the end of the sentence so it is clearly to the reader. In spoken form it is not necessary as the tone of your voice and the context of the discussion will imply that it is a question.

  • This contradicts the other answers: in this particular sentence, the two question words 什么 and 吗 clash.
    – Becky 李蓓
    Jul 4, 2020 at 9:12
  • @Becky李蓓 I think that the 吗 after 什么 has the effect of putting an emphasis on the question, although it is not necessary as someone pointed out in another answer. But language is a flexible and living thing, so is just trying to provide some other possibilities for the OP to consider. Jul 4, 2020 at 21:54

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