If引导的宾语从句和条件状语从句

2023-12-18 10:30:26 文档大全网 [ 字体：小中大 ] [ 阅读： ]

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从句,状语,宾语,引导,条件
If引导的宾语从句和条件状语从句

重点、难点

1. 含有if引导的条件状语从句的复合句中主从句的时态; 2. If引导的宾语从句与条件状语从句的区别; 考情分析

通常在单项选择、完形填空或补全、完成句子等题型中考查,分值约3—4分; 知识讲解一、 IF宾语从句

if引导的宾语从句 if意思为：是否,从句的时态通常要和主句保持一致; 例句I want to know if he lives there.

He asked me if I could help him.

考查点if、whether引导的宾语从句的区别：从含义、连词、语序和时态等方面区分; 1. 含义

if或whether引导宾语从句时,作“是否”讲,两者常可换用,在口语中多用if; 例句Nobody knows whether / if it will rain tomorrow.

Lucy asked whether / if they had a cotton sweater.

2. 与连词副词关系

if或whether既不能和that 或其他连词副词同时使用,也不能省略; 例句误 I don’t know that ifwhether he will come here today.

正 I don’t know ifwhether he will come here today.

误 He came to see what if whether there was anything wrong with his cat . 正 He came to see if whether there was anything wrong with his cat .

3. 语序

if或whether引导宾语从句时,虽具有疑问的意义,但其从句应用陈述句的语序; 例句The old woman asked me if / whether I knew the way to the hospital. 4. 时态

if或whether引导的宾语从句应和主句的时态保持一致;即主句为一般现在时,从句用任一种时态；主句为一般过去时,从句则用过去时中的任一种时态; 例句I don’t know if whether he has come here.

Tom asked if whether I had read the book. 5. 只能用whether的情况

（1）在动词不定式之前只能用whether

例句 I can’t decide whether to stay. （2）在whether …or not 的固定搭配中

例句 I want to know whether it’s good news or not. （3）在介词后,只能用whether

例句 His father is worried about whether he loses his work. （4）用if会引起歧义时

例句Could you tell me if you know the answer 这句话有两种意思： “你能告诉我你是否知道答案吗 ”或“如果你知道答案,请告诉我,好吗 ”; 如用whether则可避免歧义;

二、 IF状语从句

if引导的条件状语从句：从含义、时态和用法三个方面来研究; 1. 含义

条件状语从句是在复合句中作条件状语的句子,if作”如果、假如”讲; 例句 You will catch the bus if you get up early. 2. 时态

1主祈从现：主句是祈使句, 从句是由if引导的使用一般现在时的句子;

例句If you want to go, please tell me.

Print the photo if you like it.

2主将从现：指if引导的条件状语从句用一般现在时,主句用一般将来时;

例句If it doesn’t rain tomorrow, we’ll go to the Great Wall.

If you don’t get up early, you will be late for school.

3主情从现

当主句是一般现在时含情态动词can, may, must等的句子,从句也用一般现在时; 例句 You must see the doctor if you are ill.

3. 用法

（1）位置 if引导的条件状语从句,既可放在主句之前也可放在主句之后;当从句置于

主句之前时,常用逗号与主句隔开;

例句You will catch the bus if you get up early. =If you get up early, you will catch the bus.

（2）在if引导的条件状语从句中,当主句是一般将来时时,不能使用be going to结构,

而要用will;

例句I’ll help you with your English if I am free tomorrow.

（3）在if引导的条件状语从句中不能使用some,而要用any;

例句If you have any questions to ask, please come to my office.

（4）同义句转换,if引导的条件状语从句可转换成简单句,其方法如下： “祈使句+and/

or+简单句”结构;其中and表示句意顺承,or表示句意转折;

例句If you work hard, you’ll pass the exam. =Work hard, and you’ll pass the exam. If you don’t hurry up, you’ll be late.=Hurry up, or you’ll be late.