I’m reading Randall Munroe’s “What If 2” in Mandarin. (It’s the author of the popular cartoon xkcd.com)

There’s a chapter about placing a house-sized Jupiter in the middle of a neighborhood.

The sentence reads:

一个20,000摄氏度的氢球将以不可思议的压力向外扩张。真实的木星之所以没有爆炸,是因为 […]

Roughly: “A 20,000 degree ball of hydrogen will expand outward due to unbelievable pressure. The reason why the real Jupiter doesn’t explode is because…”

I understand that 之所以 means “the reason why”, and my dictionary confirms that.

However I don’t think 之所以 should be intended as one single word. Intuitively I can understand it as 之 + 所以 (therefore), however I’m not fully sure why it’s used as a noun modifier (木星之所以)

Can someone explain the grammar behind this construction?

  • There's also the chengyu 不知所以 = "to not know the reason / to not know what to do".
    – Becky 李蓓
    Commented Jun 27, 2023 at 7:54
  • 之所以……是因为…… is more or less a fixed phrase (固定搭配) meaning “the reason why … is because …”. Etymologically, 之所以 is comprised of 之 + 所以, but in contemporary Mandarin, it almost always occurs as a fixed phrase together with 是因为, known as a pair of “connectives” (关联词) along with 因为……所以……, 虽然……但是……, 不仅……而且……, and so on in Chinese school grammar.
    – L. F.
    Commented Jul 29, 2023 at 9:21

3 Answers 3





没有爆炸 (statement)

木星[之所以]没有爆炸 = [The reason why] Jupiter not exploded



[The reason way] the U.S. aids Ukraine is to weaken Russia

  • Is 所以 actually used as a noun in this case?
    – blackgreen
    Commented Jun 27, 2023 at 2:22
  • 所以 is acting as a noun for "reason" here. "之所以" = "reason of"
    – Tang Ho
    Commented Jun 27, 2023 at 2:36

You are almost there. 之 + 所以 = it + therefore.

  • 木星(Jupiter)之(it)所以(therefore)没有爆炸(didn't explode), 是因为(was because)...
  • "it therefore" isn't grammatical English though. I'm not sure what you are trying to say.
    – blackgreen
    Commented Jun 27, 2023 at 2:18
  • Yes, "it" shall be dropped in English. But, my main point is that "之" can be used as a pronoun, here it equates to "它" (it).
    – r13
    Commented Jun 27, 2023 at 4:07
  • I don't think this is a correct explanation.
    – blackgreen
    Commented Jun 27, 2023 at 4:13
  • Ignore the previous answer, try this: "Jupiter, therefore it didn't explode, is because of......", or this: "Jupiter, for the reason it didn't explode, is because of......"
    – r13
    Commented Jun 27, 2023 at 12:03


The reason I was late today is that there was traffic on the road.

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