We never know the great love of the parents( )we become parents ourselves.

问题描述:

We never know the great love of the parents( )we become parents ourselves.
A.until B.while C.after D.since

A
never相当于 not ever,not…… until……就是一个固定的语法结构了,直到……才……
while一般表示转折,或者后跟进行时表示正在进行的状态
after在此结构不符
since语意不符
欢迎追问,给我动力~