a.没来的及。。。就。。。

例句：

1)The roof fell before he had time to dash into the room to save his baby. 他还没来的及冲进房间救孩子，房顶就塌了。

2)He ran off before I could stop him. 我还没来的及阻止，他已经跑了。

3)To my great disappointment, my favorite singer left the concert before I could have a word with her.

让我非常失望的是，我还没有来得及和我喜欢的歌手打招呼，她就已经离开了。

b.过了多久才。。。， 动作进行到。。。程度才。。。。

例句：

1)They walked about fifty miles to the west before they saw a village. 他们西行50英里才看到一个村庄。

2)The workers worked day and night about three days before everything returned to normal. 工人们连续工作3天才使一切恢复正常。

3)He almost knocked me down before he knew it. 他几乎撞到我了才意识到。

4)We had walked a long way before we found some water. 我们走了很长的路才找到一点水。

5)Five years went by before I know it. 不知不觉，五年过去了。

c.It was + 时间段+ before… 过了多久才。。。

It was not long before … 不久，就。。。

It will (not) be +时间段+before… 要过多久。。。才。。。 (before 从句谓语动词要用一般时态)

例句：

1)It was not long before he sensed the danger of the position. 不久他就意识到他处境的危险。

2)It was five days before he came back. 5天后他才回来。

3)It will be half a year before you graduate from the school. 再过半年你才能毕业。

4)It will not be long before they understand each other. 他们大概不久就会互相了解。