题目

题型：不详难度：来源：

. It is difficult for us to learn a lesson in life __________ we’ve actually had that lesson.

A．until	B．after
C．since	D．when

答案

A。

解析

until的意思是“直到……时”“在……之前”，如：We always have to wait until the last customer has left. 我们总得等着最后一位顾客离去。