before用法小结.ppt

before 用法小结,Before 用作连词，其基本词义是“在-之前”，用来表示时间或顺序。如：Turn the light off before you sleep.睡前先把灯熄掉Think before you speak.说话之前应先想清楚但在不同的语境中before 有不同的翻译,Before 表示“不等-就-/尚未-就-”.-why didnt you tell him about the meeting?-He rushed out of the room _ I could say a word.(我还没来得及说他就冲出了房间)A.before B.until C.when D.after,before,._ I could get in a word,he had measured me.我还没来得及插上话，他就给我量好了尺寸 A.After B.When C.since D.before,2.Before 表示“不知不觉，还没弄清就-”此意常用于 before sb.know/realise-Time passed quickly and three months went by before I knew it.(时间飞快流逝，不知不觉3个月过去了)Several weeks had gone by before I realised it.(不知不觉几个周就过去了),3.Before 表示“趁-还没”Its cloudy.Take an umbrella before You regret it.(带把伞吧 以免后悔)Ill call him before I forget.(趁着还没忘记我就给他打个电话)Put that away before it gets broken.(把它收好，以免砸了),4.Before 用于这两个句型：It was/wasnt+一段时间+before 从句（过了多久/没过多久才-）一般过去时 It will/wont+一段时间+before 从句（还得过多久/用不了多久就-）一般现在时区别：It is+一段时间+since 从句,It is+一段时间+since 从句（自从有多久了）（从句用一般过去时）It was+一段时间+since从句（自从 有多久了）（从句用过去完成时）,It wasnt 3 years before we met again.(没过3年我们就又见面了)It will be two years before we meet again.(还要过两年我们才能见面)It wont be long before you regret.（用不了多久你就会后悔）We didnt wait long before he came back.(我们没等多久他就回来了),5.Before 表示“宁可-而不愿-”Id die before I apologized to them.(我宁死也不向他们道歉)They would fight to death before they surrendered.(他们宁死也不投降)We will die before we give in.(我们宁死不屈),巩固性练习1.A scientist must practise a lot _he can use all data tools well.A.as soon as B.when C.until D.before2._ she realized what was happening,she was hit over the head.A.When B.before C.since D.as,B,D,3.why didnt you help the little boy?-Oh,sorry.He had struggled to his feet_ I ran over.A.until B.after C.before D.since4.He made a mistake,but then he corrected the situation _it got worse.A.until B.when C.before D.as,C,C,5.Scientists say it may be 5 years_ it is possible to test this medicine on human patients.A.Since B.after C.before D.when6.Someone called me up in the middle of the night,but they hung up _ I could answer the phone.A.as B.since C.while D.before,C,D,7.Youd better give it up _ it is too late as its very dangerous.A.before B.as C.when D.since8.It would be months _ he was fit for work.A.until B.since C.before D.after,A,C,9.It was evening _ we reached the little town of Winchester.A.that B.until C.since D.before10.The scientists had tried out many kinds of chemicals _ they found the right one.A.since B.after C.before D.when,D,C,