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1、before 的一个特殊用法,before 的一个特殊用法,1.之前 Toms father had died before he came back.在汤姆回来之前，他父亲就已经死了。2.之后（才)It will be many years before the chemicals start to escape from the containers.（SEFCIIIA)要过很多年之后，这些化学物品才开始从容器中流出来。3.不等就 Someone called me up in the middle of the night,but he hung before I could answe
2、r the phone.（NMET 2000）半夜有人给我打电话，但还没等我去接，对方就挂断了。,一.在时态上 主句的时态可以是将来时，也可以是过去时，但从句的时态，要么是一般现在时，要么是一般过去时，根据具体情况而定。It will be 2 years before we graduate from the middle school.两年之后，我们才中学毕业。It was long before he began to do his homework.过了很长时间，他才开始做作业。,二.在句式上 主句不仅有肯定式，也可有否定式。肯定结构意义为：过多久才，需要多久才；否定结构意义为：不久就
3、 It was long before they finished their task.过了很长时间，他们才完成任务。It wasnt long before the people took up their arms.不久，人民就开始拿起了武器。,三.在用词上 在句型“long before”中，long也可换成hours,day,weeks,some time 等。It will be hours before he arrives.要过好几个小时他才会到。It will be 2 weeks before we meet again.两个星期后我们还会再次见面。It will be s
4、ome time before we know the full result.还要过一些时间我们才能知道全部结果。,四.在句型对比上 before 的这一用法与since等词用法很容易混淆，值得注意。1.It has been 5 years _ my sister returned from abroad.2.It is 5 years ago _ my sister returned from abroad.3.It was the year 1990 _ my sister returned from abroad.4.It will be 5 years _ my sister returns from abroad.A.beforeB.sinceC.thatD.when,B,C,D,A,1.我姐姐回国已有五年了。（B）2.我姐姐是在五年前回国的。（C）这是一个强调句型，如果还原的话应该是：My sister returned from abroad 5 years ago.本句就是针对5 years ago 进行强调而得来的。3.我姐姐于1990年回国。（D）本句中“it”指时间。再如：It was 5 oclock when he came back.4.要过五年我姐姐才回国。（A）,
