Recently I've been writing "should not" in Chinese a lot. But, I've been confused. What is the difference between "不该“ and "不应“? Are they both used?

For example, I know we can say


but we could also say


(Both examples from Iciba) My intuition says 不应 is more formal. Is that the only difference? Are there different usages?

  • 2
    negative case likely already covered by affirmative case, see grammars肯定形式的意思和用法很可能也包含其否定形式的意思和用法。请见"实用现代汉语语法"能愿动词 三、能愿动词分类(六)应该、应当、应,该。。。"应"和"该"不能单独回答问题,也不能用主谓短语作宾语。"应"多用于书面语,"该"多用于口语。
    – user6065
    Mar 10, 2016 at 2:31
  • My intuition is that 不应 is for instruction, and 不该 is for accusation. And accusation is just less common in formal writing.
    – user23013
    Mar 16, 2016 at 7:25

4 Answers 4


Generally speaking, "不应" is used more frequently in formal writing, while "不该" is used in oral expression.

If it's hard for you to determine formal or non-formal, consider this, use 不该 for subjective, and use 不应 for objective case.


I agree that "不应" is more formal, and I also agree that it seems to be the biggest difference - at least in common use cases. I have a feeling that "不该" is more objective while "不应" is a little bit subjective, but didn't find any reference for this - probably it's just a side effect of being formal/informal.

For example, your first case is likely to happen in oral expression, and the second case is likely to happen in a public speaking or a written essay.

By the way, I think the combined word "应该" can be used to replace either "应" or "该", so there shouldn't be very big differences.


Aside from the formal/informal issue, I think another distinction is that 不该 is more suited for an event in the past that "should not have" happened. Using 不应 for this situation sounds awkward, if not wrong, to me. This may have something to do with the objectiveness/subjectiveness @bfrguci mentioned, since "should not have" is not an objective description of reality, but rather an opinion and judgement.

  • jukuu:should not have happened,4 results, only one relevant: 。。。things should not have happened in this way。。。发生这样的事情实在太不应该了
    – user6065
    Mar 11, 2016 at 4:16
  • @jukuu: Good example, but I believe it is a slightly different situation from what OP proposed: 不应 and 不该 is usually followed by an action. If there is no such action or the action is mentioned before, then it looks like the full form 不应该 should be retained. Mar 12, 2016 at 16:52

"不应" or "不该" is short for "不应该", so you should use "不应该" in formal writing.

For example:


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