串讲四六级语法第五讲条件目的状语从句.ppt

十四节课串讲四六级语法第5讲条件、目的状语从句 豌豆群： 群：66437760,专题一、条件状语从句,一、条件状语从句 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，主句是一般将来时态，从句要用一般现在时,祈使句或情态动词主将从现原则（主将从现，将并非指将来时，还只表示将来含义的，跟着if后的那句话是从句。）,二、条件状语从句（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。如： 1） If you ask him , he will help you. 2） If you fail in the exam ，you will let him down. 另外，if从句还表示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. I would have arrived much earlier if I had not been caught in the traffic.,三、引导词 引导条件状语从句的连词有：if（如果），unless（除非；如果不），as long as（除非；只要），supposing（假设），on condition that（条件是），in case（如果）。这些词由于出现的频率较小，且用法较复杂一些，所以不如if为大家所熟知罢了。下面就这些词的用法以例句的形式进行一下简单总结。 1、unless conj.除非，若不，除非在的时候 You will fail to arrive there in time unless you start earlier. Unless it rains , the game will be played.,2、on condition(that).在条件下，如果 on condition (that).引导的条件从句是主句事件发生的前提条件或唯一条件。 I can tell you the truth on condition that you promise to keep a secret. You can go swimming on condition (that) you dont go too far from the river bank. 3、supposing conj.如果，假如 supposing引导的条件从句表示一种假设条件。 Supposing it rains, shall we continue the sports meeting? Supposing anything should go wrong , what would you do then?,4、provided conj.假如，除非，以为条件 provided (that) +从句表示一种假设条件。 He will sign the contract provided we offer more favorable terms. He wont be against us in the meeting provided that we ask for his advice in advance. 从上述例句可以看出if, unless, on condition (that), supposing, provided等词引导的条件状语从句，主从句条件关系分明，结构清晰。 但有些句子，虽没有含条件关系的连词，却也隐含着条件关系，这些句子常用一些词，如but for , without等引出一个介词结构来表示条件，条件常常是虚拟的，或与事实相反的假设。,如：but for若非，要不是 But for the rain, we should have a pleasant journey. But for your help, we should not have finished in time. You must speak louder so that /in order that you can be heard by all. He wrote the name down for fear that(lest) he should forget it. Better take more clothes in case the weather is cold.,专题二、目的状语从句,一、目的状语从句定义 目的状语从句：从句部分是用以补充说明主句中谓语动词发生的目的的。 引导目的状语从句常用的连词有： that（以便），so that（以便）， in order that（为了；以便），Lest（免得；唯恐）， for fear that（生怕；以免）。 目的状语从句的谓语常含有 may, might, can, could, should, would You must speak louder so that /in order that you can be heard by all. He wrote the name down for fear that(lest) he should forget it. Better take more clothes in case the weather is cold.,学习目的状语从句应注意以下两点： （1）目的状语从句中常含有can , could, may, might, should等情态动词。 I got up early so that I could catch the first bus. （2）在口语中so可以引导目的状语从句。 Well sit nearer the front so we can hear better. 【注意】in order that与in order to的区别： in order that+从句 in order to+动词原形 （ in order to后面加的那个不叫目的状语从句，叫目的状语）,练习题,1.(07全国26) I wont call you，_ something unexpected happens. A. unless B. whether C. because D. while 2.(07湖南33) Most brids find it safe to sleep in the trees，but _ they have eggs or young chicks，they dont use a nest. A. why B. how C. unless D. where 3 My parents live in a small village. They always keep candles in the house _ there is a power out. A .if B. unless C in case D. so that,4 In time of serious accidents，_ we know some basic things about first aid，we can save lives. A. whether B. until C. if D. unless 5.(05北京33) Id like to arrive 20 minutes early _ I can have time for a cup of tea. A. as soon as B. as a result C. in case D. so that,6.(08山东31) Youd better not leav