before的用法

Answer 1

before 用作连词，常用于过去时，将来时等。例如：
before用作连词时，意思是“在„„之前；还没来得及 „„ 就”。
Before I could say a word, she had stormed out of the room.
不等我说一句话，她就冲出了房间。
Don’t count your chickens before they are hatched.
不要高兴得过早
用于It + be + 时间段+ before...句型中，意思是“在„„之后才„„”
It will be five years before I come back.
我五年后才能回来。
It was not long before the enemy was driven out of their country.
不久之后，敌人就被赶走了。
还有“趁„„（还没有）”
They are thinking of buying the house before the prices go up.
他们正在考虑趁房价未涨时把房子买下来。
Do it before you forget it.
趁早动手，以免忘了。
before 用作副词，常用完成时。例如：
I’ve seen the film Titanic before.
我以前看过《泰坦尼克》这部电影。