之所以 zhī suǒ yǐ — (after a noun N and before a predicate P) the reason why N P
义项
(after a noun N and before a predicate P) the reason why N P
(after a noun N and before a predicate P) the reason why N P; Example: 我之所以讨厌他 "the reason why I dislike him (is ...)"
conjunction