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1、精品文档Chapter 1 语法If 和 unless 引导的条件状语从句我们用 if 引导的条件状语从句来讨论可能的条件以及该条件成立时可能的结果。 一. 学习 if 引导的条件状语从句的用法，我们可先从如下的口诀入手：If 条件句不一般，几个要点记心间；条件句，放在前，逗号要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。We can walk there if we cant find a bus. 如果我们找不到公车，也能走路去那里主句条件状语从句If it rains tomorrow, we will not go to the zoo. 如果明天下雨，我们就不去
2、动物园条件状语从句主句What will you go if you find someone in danger?主句条件状语从句如果你发现某人有危险，你会怎么做？If 条件句有不同的类型，简述如下：1. 用 if 条件句表达客观真理或普通现象If 条件句用于表达客观真理或普通现象时，主，从句时态均用一般现在 时，如： Eg. If you freeze water, it turns into ice.A fish dies if you take it out of water.2. 用 if 条件句表示将来可能发生的事情在表示将来可能发生的事情的 if 条件句中，主句用一般将来时，而
3、if 从句用 一般现在时表示将来的时间，即主将从现Eg. If I like the house, I will buy it. 如果我喜欢这房子，我就会把它买下I will tell her if I see her. 如果我见到她，我就会告诉她。主句中的 will 也可以用情态动词 can, may 或 might 等代替。如：Eg. If they are friendly ，I might invite them to the party. 如果他们很友善，我可能 会请他们去参加聚会If we hurry now, we can stop for coffee later. 如果我们现
4、在抓紧时间，就可以稍后精品文档精品文档去喝咖啡注意：在条件句中，主句部分只能使用动词 will 的一般将来时，不能使用 be going to 的结构二. Unless 的条件句表示在特定条件下，才决定做或不做一件事，中文用的连接词一般是“除非”和 “否则”。如：除非刮台风，否则演唱会将如期进行。在英语中，我们可以用 unless 表达这个意思，相当于 if not。以这个句子为例：The concert will be held as schedule unless there is a typhoon.= the concert will be held as schedule if th
5、ere is not a typhoonShe will keep on singing unless she is told to stop. 她会一直唱下去，除非有人叫她 停止= she will keep on singing if she is not told to stop也可以用 or(否则) 来做同义句转换Unless you listen carefully, you wont know the answer.= if you dont listen carefully, you wont know the answer.= you should listen careful
6、ly, or you wont know the answer.精品文档精品文档深圳中考题：1. If I _ his phone number, I will tell you.A. find B. found C. will find D. have found2. We will go camping if it _ tomorrow.A. Wont rain B. didnt rain C. doesnt rain D. isnt raining3. Im waiting for my friend. If he _, I _ swimming alone.A. doesnt come
7、; will go B. wont come; will goC.will come; wont go D. dont come; will go4. _ you go to the supermarket at 7 p.m, you can buy a lot of cheap food.A. If B. Unless C. Whether D. When5. I wont get to the party on time _ I catch the first train tomorrow morning. A. If B. Unless C. Whether D. When5. -Sha
8、ll we go on a picnic this weekend?-Good idea! Unless it _.A. rains B. doesnt rain C. rain D. wont rain7. -Can I change the jacket for another one _ it doesnt fit me well?- Of course.A. unless B. if C. that D. though8. Nobody can learn maths well he works hard on it.A if B unless C thought D however9
9、. If fish away from water, they die.A are taking, wont B are taken, willC are being taken, will D take, wont10. Each student can ask teachers for help if he how to work out the problem.A will know B wont know C dont know D doesnt know精品文档精品文档诚信笃行勤奋一A 用 if 或 unless 填空1. he wants to see me, you can te
10、ll 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 examination she is ill.5. I ll take that computer I have enough money.6. my grandma wears glasses, she can see better.7. I wont buy that backpack it costs less than $
11、208. I m tired; I ll have a rest for tea.9. You won t get paid for time off you have a doctor s note.10. you will get a toothache you do clean your teeth regularly.B 用所给单词的适当形式填空1. If he (get) a low mark in the test, he (study) harder.2. If you (swim) every day this summer, you (be) very healthy. 3.
12、 If he (not hurry), he (not see) the beginning of the match. 4. You can t go out unless you (finish) your homework.5. Unless I save my money carefully, I (not be) able to buy a football.6. If it (not rain) tomorrow, we (go) to the park.6. If he (return) to the school, I (let) you know.7. He smoking
13、unless he (have) enough money.8. They can remember it better if someone (give) them some advice about it.9. The man (set off) if he (buy) the air ticket.二 解释句子1. you will feel worse unless you take more rest.2. you will be late for work if you dont hurry up.3. no one is going to help you unless you change your mind.精品文档18926518344 838722501精品文档精品文档