(1) before sb can/ could … 某人还没来得及……
例:Before I could get in a word ,he had measured me.
我还没来得及插话,他就给我量好了尺寸。
(2) It will be 时间 before 从句; 还有多长时间……
例:It will be 4 years before he graduates.
他还有四年时间变毕业了。
(3) had done some time before (才……)
例:We had sailed four days and four nights before we saw land.
我们航行了四天四夜才见到陆地。
(4) had not done ... before ... 不到……就……
例:We hadn’t run a mile before he felt tired.
我们还没走到一英里路就觉得累了。
(5) It was not 一段时间 before 不多久就……
例:It wasn’t two years before he left the country.
还没到两年他们离开了那国家。