(1) before sb can/ could … 某人还没来得及……
例:Before I could get in a word ,he had measured me.
(2) It will be +时间+ before + 还有多长时间……
例:It will be 4 years before he graduates.
(3) had done some time before (才……)
例:We had sailed four days and four nights before we saw land.
(4) had not done ... before ... 不到……就……
例:We hadn’t run a mile before he felt tired.
(5) It was not +一段时间+ before 不多久就……
例:It wasn’t two years before he left the country.