- 之所以 zhīsuǒyǐ the reason whyUsed in the first part of a sentence to state a result, while the second part explains the cause, often paired with [[是因为|是因為|shi4 yin1 wei4]].
- 所以然 suǒyǐrán the why and whereforethe cause, reason, or underlying logic of a situation
- 忘乎所以 wànghūsuǒyǐ to get carried awayto forget oneself or lose all perspective because of excessive excitement, pride, or success
- 不知所以 bùzhīsuǒyǐ to not know why(idiom) to not know the reason why something is the case; to not know the cause of a situation
- 知其然而不知其所以然 zhīqírán'érbùzhīqísuǒyǐrán to know the result but not the causeA saying meaning to know that something is the case without knowing why it is so; to understand the what but not the why.
- 忘其所以 wàngqísuǒyǐ to forget oneselfto get carried away or lose self-control due to extreme excitement or pride
- 因为...所以 yīnwèi... suǒyǐ because ... thereforeconjunction used to express causality by introducing a reason and its consequence
