before句型
before sb can/ could 某人还没有来得及
例：Before I could get in a word ，he had measured me.
我还没有来得及插话，他就给我量好了尺寸。
It will be +时间+ before + 还有多久
例：It will be 4 years before he graduates.
他还有四年时间变毕业了。
had done some time before
例：We had sailed four days and four nights before we saw land.
大家航行了四天四夜才见到陆地。
had not done ... before ... 不到就
例：We hadnt run a mile before he felt tired.
大家还没有走到一英里路就感觉累了。
It was not +一段时间+ before 不多长时间就
例：It wasnt two years before he left the country.
还没有到两年他们离开了那国家。
