Before 在英語(yǔ)中是一個(gè)比較常用的虛詞,它既可作介詞或副詞用,也可作從屬連詞用.在近幾年的高考試題中常常出現(xiàn)考查其從屬連詞用法的題目.下面就把其作為從屬連詞的用法歸納如下：

　　1.表示“在…..之前就…..”.

　　Mary had finished her homework before her mother returned.

　　2.表示“過(guò)了多久后才……..,動(dòng)作進(jìn)行到什么程度才……”

　　The man almost knocked me down before he saw me .

　　They walked about 30 miles to the west before they saw a village .

　　They worked day and night about three days before everything returned to normal .

　　3.表示“來(lái)不及; 尚未…..就…”

　　Before I could get in a word ,he had measured me .

　　He ran off before I could stop him .

　　She left the company before I could have a word with her .

　　4.表示“剛…就…”

　　I had hardly sat down before the bell rang.

　　5.表示“不知不覺(jué)就…..; 還沒(méi)弄清就……”

　　Time passed quickly and three months went by before Aqiao knew it.

　　6.表示“寧愿…,決不…,與其…,毋寧….”常與will 或would 連用.

　　I would die before I would tell

　　I’d shoot myself before I apologized to him.

　　I would / will die before I surrender .

　　7.表示“否則;以免”

　　Do it now before you forget .I will write it down before I forget it .

　　8.用于句型“it was +時(shí)間段+ before …” 表示 “過(guò)了多久才…”

　　It was three days before he came back..

　　9.用于句型 “ it was not long +時(shí)間段+ before …” 意為“不久就….”

　　It was not long before he sensed the danger of the position .

　　10.用于句型“it will be(not )+時(shí)間段+ before….”表示“要過(guò)多久/ 不久…才…”

　　It will be half a year before you graduate from this school .

　　It will be not long before you find you are wrong .