帮我看看下面的语法有木有错误~
It was/will be +some time +before
分解开看就是：It will be +some time +before+…+does/do
例句:It will be one and a half years before I leave school.还有一年半时间我就要毕业了.
It was +some time +before 过了多久才
例句：It wasn’t long before he told me that.没过多久他就把那件事告诉我了.
It was/will be +some time +before
要区别于It is/has been +some time +since +did（注意动词的时态）
例句：it has been two years since I met him last time.自从上次碰到他后已经过去两年了.也就是说有两年没见面了.
It has been two months since my father smoked(延续),译为：戒烟
It has been two months since my father began to smoke(瞬间),译为：吸烟