(完整word)八年级条件状语从句讲练(附答案)

引导条件状语从句的连接词主要有：if(如果）、unless（除非）或as long as（只要）等。unless 在意思上等于if...not。

一、条件状语从句用法

1、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:

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。

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.如果我是你,我会邀请他参加聚会。

2、unless = if...not.除非,若不,除非在……的时候

例如：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.

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

3、so/as long as只要

例句;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。

So long as you’re happy, it doesn’t matter what you do.

只要你高兴，你做什么都没有关系。

二、时态问题

在条件状语从句中，要注意“主将从现”的规定，即主句用一般将来时，从句用一般现在时表示将来时。例句：I will come to see you if I have time. 我有时间，我就来看你。

常见考法

对于条件状语从句的考查，多以单选和完形填空的形式，从时态的角度设题，考查学生灵活运用的能力，或从连词的意义角度让大家选择连词。

典型例题：If he ___in half an hour,we ___wait for him.

A. won't come ,won't

B.won't come ,don't

C.doesn't come ,won't

D.will come ,don't

解析：本题考查条件状语从句“主将从现”的运用。题干的意思是“如果他一小时后不来，我们将不会等他了”，从“in half an hour”，“一小时后”可知本句说的是未来的事，那么if引导的条件状语从句要用一般现在时表示将来时，主句要用一般将来时。

答案：C

误区提醒

if 既可以引导条件状语从句，表示“如果”，也可以引导宾语从句，表达“是否”。辨别它在这两种从句中的时态是我们经常容易出错的地方。另外，if 和unless的用法也需注意。

典型例题：----I wonder if your wife to the party.

----If your wife _________, so will mine。.

A. will go，go

B. will go, goes

C.goes, will go

D. will go, will go

解析：第一句中if表示“是否”，引导宾语从句，用将来时will go；第二句“如果你的妻子去，我的妻子也去”，if引导条件状语从句，用一般现在时表示将来时。your wife，单三人称主语，所以用goes 。

答案：B

一、If引导的条件句

*引导条件状语从句最常用的连词是if。 if 引导的条件句有真实条件句和非真实条件句两种（非真实条件句会在以后的虚拟语气中阐述），其引导的真实条件状语从句表示在某种条件下某事很可能发生。

1、“if从句（一般现在时）+主句（一般现在时）”的条件句----表达真理或事实（动作必然发生）。

If you heat ice, it turns into water.如果你加热冰，它就会变成水。

If you put suger into water, it disappears.如果你把糖放进水里，它就会溶解。

2、“if从句（一般现在时）+主句（一般将来时）”的条件句----谈论可能发生的事情。

If it rains tomorrow, we’ll stay at home.如果明天下雨，我们会呆在家里。

If I don’t hear from him, I won’t go. 如果没接到他的通知，我不会去。

【注】这类条件句主句部分还可以用情态动词，如

I may buy a car if I pass the driving test.如果通过驾驶考试，我可能会买一辆车。

If you go to another country, you must obey the local laws.如果你去另一个国家，就必须遵守当地的法律。

3、有时if引导的条件句可以与“祈使句，and/or…”相互转换，

If you don’t hurry up, you will miss the bus.

=Hurry up, or you will miss the bus.快点，否则你会错过这趟车。

If you use your head, you’ll find a way.

=Use your head, and you will find a way.动动脑子的话，你就会想出办法。

二、unless引导的条件状语从句

unless意为“除非、如果不”，用来引导否定意义的条件句，等于“if…not…”

Let's go out for a walk unless you are too tired.

= If you are not too tied, let's go out for a walk. 我们出去散步吧，除非是你太累。

Unless you brush your teeth every day, you will get a toothache.

=You will get a toothache if you don’t brush your teeth every day. 如果不每天刷牙，你就会牙疼。

用unless改写句子

1. If you haven't listened carefully, you won't know how to do the exam questions.

2. If I don't leave now, I will be late.

3. We will get lost if we don't have a map.

4. If you don't return your book to the library today, you will be fined.

5. I will buy that dress if someone hasn't bought it already.

用if 或unless填空

1. _______he wants to see me, you can tell him to wait.

2. _______it snows tomorrow, we’ll have a day or two off.

3.We won’t go to his party_______he invites us.

4.She is sure to pass the exam_______she is ill.

5. _______I’m tired, I’ll have a rest for tea.

6.I won’t buy that backpack_______it costs less than 100 yuan.

7. I will lend you the money_______you pay back on time.

8. You will fail the exam_______you study hard.

9.I will buy a computer_______I am able to save enough money.

10. _______you drop a glass, it breaks.

单选

1. If I ________ his phone number, I will tell you.

A. find

B. found

C. will find

D. have found

2. We will go camping if it _______ tomorrow.

A. Won’t rain

B. didn’t rain

C. doesn’t rain

D. isn’t raining

3. I’m waiting for my friend. If he _______, I ______ swimming alone.

A. doesn’t come; will go

B. won’t come; will go

C.will come; won’t go

D. don’t come; w