时间状语从句since和before的区别（重磅考点Itbe一段时间）

此时before直到……才，过了……才，

相当于until

当强调主句所表达的时间、距离很长或花费的精力相对比较小时：

It will be five years before we meet again.

要等5年我们才能再相见。

It was several moments before he realised that Rom and Hermione were at his side.

过了好一会他才意识到罗恩和赫敏站在他旁边。《哈利波特与死亡圣徒》

It was some time before the door opened in response to his ring.

他按完门铃后过了一会儿门才打开。

It may be many years before the situation improves.

这种状况或许要过很多年才能得到改善。

It was some time before I realized the truth.

过了很长一段时间我才悟出真相。

It was many years before the full story was made public.

许多年之后，事情的全貌才公之于众。

It will be months before we get the results.

我们要等很长时间才能得到结果。

It was three days before came back.

过了三天他才回来。

分析：

在It be/take 时间段 before这一句型中又可以根据主从句的时态分成两种情况。

若主句是一般时将来时态，从句是一般现在时.若主句是肯定句意思是“要过多长时间才”;若主句是否定形式翻译成“用不了多久就”。

It will be two weeks before everything returns to normal.

两周之后一切才能恢复正常。

It will be many years before the situation improves.

这种状况或许要过许多年才能得以改善。

It won't be long before we meet again.用不了多久我们就会再见面的。

这时若主句是一般过去时从句也是一般过去时。若主句是肯定句翻译成“多长时间之后才”，若主句是否定形式翻译成“没过多久就”。如：

It was some time before I realized the truth.

过了很长一段时间我才了解到真相。

It wasn't long before she became a brave solider.

没过多久她就成了一名勇敢的战士。

After that it still took seven years before they got married.

他们又过了七年才结婚。

注意：当主句的谓语动词为延续性动词时，before与until有时可以互换。

It was an hour before/until the police arrived.

过了一个小时警察才赶到。

It will be some months before we graduate from school.

过几个月，我们就毕业了。)

Shall we see him again? 我们还能见到他吗？

I think so. It won’t be long before he comes back to the hometown.

我想会的，过不了多久他又返回家乡。

该句型中的时间长为long, a long time, years, months, weeks, days, hours, minutes等时间段。此句型容易与强调句型混淆，试比较：

It was two years before he came back from abroad.(过了两年他才从国外回来。)

It was two years later that he came back from abroad.(两年之后他才从国外回来。)

第一句为状语从句，it 表示时间；第二句为强调句型，强调的是时间状语two years later。

　　高考真题巩固练习

⒈It was evening ________ we reached the little town of Winchester.

A.that B.until C.since D.before

2.It was some time _______ we realized the truth.

A.when B.until C.since D.before

3. -How long do you think it will be __ china sends a manned spaceship to the moon?

　　-Perhaps two or three years.

A.when B.until C.that D.before

　　参考答案：DDD

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