同学你好，该知识点来自沪江网校《英语零基础直达大学六级【爆款特惠班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
before在……之前
before the girl was able to explain what had happened to her 在女孩能讲述她的经历之前
Nearly a week passed 一周已经过去了
这里就是说，女孩讲述之前，已经过去了一周。

如果这里用after，就成了她讲述之后，过了一周。

再看看其他例子：
Annie was born a few weeks before Christmas.
安妮在圣诞节前几个礼拜出生。
Stock prices have climbed close to the peak they'd registered before the stock market crashed in 1987.
股票价格已经快爬升到了1987年股市崩溃前的最高纪录。

After May 19, strikes were occurring on a daily basis.
在5月19日以后，罢工每天都在发生。
After Don told me this, he spoke of his mother.
唐告诉我这件事以后，他谈到了他的母亲。


这里必须有before连接主句和从句的。

祝同学学习进步~