2015-12-20条件状语从句1、定义由引导词if或unless引导的状语从句叫做条件状语从句。

在英文中，条件是指某一件事情实现之后(状语从句中的动作)，其它事情(主句中的动作)才能发生，通常译作"假如"。

(注意:在含有条件状语从句的复合句中，表示将来时态，主句是态,或谓语动词是，从句要用态,即[原则]。

Eg1: Take the medicine, you will be fine.Eg2: If you can read as many English books as possible, your English will be improved.2、用法语法引导条件状语从句最常用的连词是if, 由if引导的条件状语从句表示在某种条件下某事很可能发生if引导的条件状语从句既可以将从句放前面也可以将从句放后面。

除了if 之外，还有其他连词也可以引导条件状语从句。

【注：在条件状语从句中，绝大数情况下some要变为any。

】(1) unless conj.除非，若不，除非在……的时候Eg1: You will fail to arrive there in time unless you start earlier.如果你不早点动身，你就不能那儿。

Eg2: Unless it rains, the game will be played.除非下雨，比赛将照常进行。

(2) on condition(that)...在……条件下，如果on condition (that)...引导的是主句事件发生的前提条件或唯一条件。

Eg1: I can tell you the truth on condition that you promise to keep a secret.我可以告诉你真相，条件是你答应保密。

Eg2: You can go swimming on condition (that) you don't go too far from the river bank.你只有在不远离河岸的条件下才可以下水游泳。

Attention（注意）：①unless = if...not. Eg: Let's go out for a walk unless you are too tired.If you are not too tired, let's go out for a walk.②if 引导的有和两种：真实条件句Eg：If it rains tomorrow, we won’t go on a park非真实条件句是的一种，表示与事实相反，主句用would do，从句用过去式，具有假设性，一定不会是真的,即所假设的事情基本不会有发生的可能。

Eg：If I were you, I would go with him.③so/as long as （只要）、in case（万一）引导。

Eg1: So long as you’re happy, it does n’t matter what you do. 只要你高兴，你做什么都没有关系。

You may borrow my book as long as you keep it clean只要你保持书的清洁，你就可以把我的书借去。

Eg2: Take your umbrella in case it rains. 带着你的伞吧，以防下雨。

④“祈使句+and / or+简单句”。

其中and表示句意顺承；or则表示转折，意为“否则”。

Eg1:If you work harder, you’ll pa ss the exam.= Work harder, and you’ll pass the exam. 如果你再努力些，你就会通过考试。

Eg2: If you don’t hurry up, you’ll miss the train.= Hurry up, or you’ll miss the train. 如果你不快点儿，你就赶不上火车了。

3、练习题Ⅰ.单项选择1 .If you _____ to the party, you’ll have a great time.A. will goB. wentC. goD. going2. It will be a long time ____ Peter _____ his work.A. since, has finishedB. after, finishesC. when, will finishD. before, finishes.3. What will father _____ us from Japan?A. takeB. bringC. carryD. make4．I ____ her the answer if she ____me.A. can tell, will askB. will tell, will askC. would tell, askD. will tell, asks5. – What are you going to do tomorrow? --We’ll go to the library tomorrow if it ____.A. isn’t rainB. rainC. won’t rainD. doesn’t rain6.—Do you know when he will come back tomorrow? --Sorry, I don’t know. When he ____ back, I’ll tell you.A. comesB. will comeC. comeD. may come7. What will you do if you _____ to the old folk’s home visit?A. goB. wentC. goingD. will go8. If I eat ____ food, I’ll be very fat.A. too manyB. many tooC. too muchD. much too9. I’ll give the book to him if he ___ here next Sunday.A. will comeB. comesC. is comingD. came10. There ____an English film in our school tomorrow.A. is going to haveB. will haveC. is going to beD. has11. Could you tell us where ____？A. will the next Olympic Games heldB. the next Olympic Games will be heldC. would the next Olympic Games be heldD. the next Olympic Games would be held12. When my mother returned last night, I ____ a book.A. readB. am readingC. was readingD. am going to read13. What ____ you ____ when it began to rain?A. do, doB. were, doingC. are, doingD. did, do14. I’ll wake you up when he ____back.A. willB. is going to comeC. comesD. comeII. 同义句转换1. Run fast, or you’ll be late for school._______ you _______ _______ fast, you’ll be late for school.2. You can buy the dictionary if you take enough money with you.Take enough money with you, ______ _____ ______ buy the dictionary.3. If there is no air, none of us can live.None of us can live _______ _________.Ⅲ、用所给词的适当形式填空1.If you ______(feel) tired, you _____ (have) to have a rest.2. Where _____ he ____(see) the film if he _______(have) time?3. If there ____(be) fewer trees, there ____( be) more pollution.4. He ___ (dress) more casually if he ___( not work) on weekends.5. If Marcia ______ (live) alone, she _______( keep) a pet parrot.6. Lana ___（buy）a new dress if the old one ___(be) out of style(过时).7. The twins ______(fight)（打架）if they_____(argue).8. Peter ____( send) me a beautiful souvenir （纪念品）if he ____(tour) Spain.9. If Mr Green _______ (say) I am hard- working, my parents ___( feel) glad.10.I ______(go) to the beach if it______( not rain) this week.11. _____they ___( have) a match if the P.E. teacher __(be) busy?12.He ____(write) a letter to his grandparents if he ____(get) his report card this week.13. If she ____(get) up late, she ____( not catch) the early bus.Ⅳ.完成句子1.如果他到得晚了会发生什么事情？What ______ ______ if he ______ late?2. 如果努力学习，你就会取得好成绩。