条件状语从句讲解(基础版本).doc

条件状语从句讲解if引导的条件状语从句（注意&练习）在句子中做条件状语的从句称为条件状语从句。可置于句首、句尾，有时还可置于主语和谓语之间。引导条件状语从句的连接词有：if ,unless,as/so long as等 1.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 we pay much attention to the earth, well have a better world. 如果我们多关爱地球，就会拥有一个更美好的世界 If it rains tomorrow, what shall we do? 如果明天下雨，我们怎么办？ 注意：if还可以引导虚拟条件句，表示不可实现的条件，从句中多用一般过去时或过去完成时。What would happen if there were no water ?如果没有水会怎样？2.unless引导的条件状语从句unless的意思是如果不，除非。可与if.not互换。You will fail in English unless you work hard.你英语考试会不及格的，除非你更加努力。3.as /so long as引导的条件状语从句 as /so long as意思是“只要”So long as youre happy,i will be happy.只要你高兴，我就高兴。4.once引导的条件状语从句once引导的条件状语从句，意为“一旦.，就”，从句可置于主句前或后Once you begin,never stop.一旦开始，就绝不要停止Maths is easy to learn once you understand the rules.一旦你理解了规则，数学就不难学了。提示：在条件状语从句中，用一般现在时代替一般将来时，用一般过去时代替过去将来时。If the weather is bad next week, well put off the climbing.如果下周天气不好，我们将推迟爬山。Father told me if I worked hard he would buy me a gift.爸爸告诉我，如果我努力学习，他会给我买一份礼物。注意 ：学习 if 引导的条件状语从句的用法,现在总结一下: if 条件句不一般,几个要点记心间; 条件句,放在前,逗号要放句中间。 条件句表可能，主句多用将来时； 条件句表事实，主句常用现在时。在 if 引导的条件状语从句中，如果从句谈论的是一个有可能发生的事实及其产生的相关的结果，主句用一般将来时态，从句用一般现在时态。如： We can walk there if we cant find a bus . If it rains tomorrow ,we will not go to the zoo. What will you do if you find a panda in danger.如果 if 条件句谈论的是重复发生和预示要发生的情景和事件，则主从句大多用一般现在时态。如： If bears are in danger ,they attack people.在 if 引导的条件状语从句中，if 和条件句位置灵活，可直接放在主句后面，若 if 条件句放句首， 从句后面要加逗号，和主句隔开。还要注意前后时态一致原则if 条件状语从句的时态练习 一在正确的答案下划一条线。1.Daina ( will go/go/goes) to Europe if she (will pass/pass/passes) the exams .2. The graduates (will teach/teach/teaches) in the poor village if the Ministry of Education (will agree/ agree/agrees) soon.3. If there (will be/ are/is) a car accident, they (will call/call/calls) 110 for help at once.4. If it (wont/dont/doesnt/ isnt) rainy, we (will take/ take/takes) walk outside.5. If a UFO (will land/land/lands) in front of me, I (will go/go/goes) in to look for the alien.6. If he (will have/have/has) money, he (will bulid/build/builds) a science lab.7.Dont wait for me if I (am/ will be) late.8.They (wont/dont) go to the beach if it (will rain/rain /rains).9. I (will call/ call) you if he (will stay/stay /stays) at home.10. Mr Smith (will let/ let/lets) you know if he (will need/ need/ needs) help.11. (Will / Do/ Does) he visit the museum if he (wont / dont/ doesnt) get tired?12. Where (will/ do/does) they live if they (will miss/ miss/ misses) the bus?状语：状语是句子的重要修饰成分。状语是谓语里的另一个附加成分,它附加在谓语中心语的前面,从情况,时间,处所,方式,条件,对象,肯定,否定,范围和程度等方面对谓语中心进行修饰或限制。用来说明地点、时间、原因、目的、结果、条件、方向、程度、方式和伴随状况等。状语一般由副词、介词短语、分词和分词短语、不定式或相当于副词的词或短语来担当。其位置一般放在句末，但也可放在句首或句中。副词是一种用来修饰动词,形容词,副词或全句的词,说明时间,地点,程度,方式等概念。1.副词一般在句子中做状语He speaks English very well. 他英语说得非常好.中的very是程度副词，用来修饰well。very well是修饰speak的程度状语。He is playing under the tree.他在树下玩儿.中的under the tree是地点状语.2. 不定式在句子中可以作目的状语。I come specially to see you.我专门来看你.3.介词短语Ten years ago, She began to live in Dalian.The boy was praised for his bravery.4.从句作状语When she was 12 years old, she began to live in Dalian.If I am not busy tomorrow, I will play football with you.5.分词作状语Having had a quarrel with his wife, he left home in a bad temper。Inhibited in one direction, it now seems that the Mississippi is about to take another.在复合句中，由从句表示的状语叫做条件状语从句。它可以用来修饰主语中的动词.形容词.副词等。根据它表达的意思，状语从句可以分为时间状语从句，原因状语从句，条件状语从句，比较状语从句，目的状语从句，结果状语从句和让步状语从句等。定义由连接词if或unless引导的状语从句叫做条件状语从句。（注意：在含有条件状语从句的复合句中，如果主句是一般将来时态，从句要用一般现在是主将从先原则)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，如果，除非”。引导词：常用引导词： if , unless特殊引导词: as long as（除非；只要），supposing（假设），on condition that（条件是），in case（如果）条件状语从句的位置可放在句首或句尾，放在句首时常用逗号与主句隔开。If 引导词用法if 引导的条件句有：真实条件句和非真实条件句两种:1.真实条件句：表示在某种条件下某事很可能发生。如: If you ask him, he will help you.如果你请他帮忙,他会帮你的。 If you fail in the exam, you will let him down.如果你考试不及格,你会让他失望的。If it rains tomorrow, we wont go on a picnic. 如果明天下雨，我们就不去野餐。注意：在含有条件状语从句的复合句中，表示将来时态，主句是一般将来时态，从句要用一般现在时主将从现原则，并且，切记紧跟着if的那句话是从句。） 2. 非真实条件句是虚拟语气的一种，表示与事实相反 ，不可实现的条件或根本不可能存在的条件,也就是一种虚拟的条件或假设,从句多用一般过去时或过去完成时。如: If I were you, I would invite him to the party.如果我是你,我会邀请他参加聚会。 I would have arrived much earlier if I had not been caught in the traffic. 如果没有堵车,我会到的早一点儿。 If I were you, I would go with him.如果我是你,我会和他一起去的。unless引导词用法固定搭配： unless = if.not 除非,若不,除非在的时候You will fail to arrive there in time unless you start earlier.If you dont start earlier, you will fail to arrive there in time.如果你不早点动身,你就不能及时赶到那儿。 Unless it rains, the game will be played.If it dosent rain，the game will be played.除非下雨,比赛将照常进行。 Lets go out for a walk unless you are too tired. If you are not too tired, lets go out for a walk. 经典语句：If it dosent rain tomorrow,we will go to the zoo.条件状语从句就是用以表示“在某种条件下,会”由as (so) long as, in case引导。So long as youre happy, it doesnt 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。Take your umbrella in case it rains.带着你的伞吧，以防下雨。完成下列句子 1。如果你请求他，他会帮你的If you _him, he _ _you2。如果她早点儿起床，就有时间在家里吃早餐 If she_ _a little earlier, shell have time to eat breakfast at