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1、Chapter1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 can t 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，我们就不去动物园条件状语从句主句What
2、 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if从句用一般现在时表示将来的时间，即 主将
3、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.如果我们现在抓紧时间，就可以稍后去喝咖啡注意：在条件句中，主句部分只能使
4、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 there is not a typhoonShe will keep on singing
5、 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 won t know the answer.= if you don t listen carefully, you wont know the answer.= you should listen carefully, or you wont know the answer.深圳中考题：1. I
6、f I _ his phone number, I will tell you.A. findB. foundC. will findD. have found2. We will go camping if it _ tomorrow.A. Wont rainB. didnt rainC. doesnt rainD. isn3. I m waiting for my friend. If he _, I _ swimming alone.A. doesnt come; will goB. wont come; will gocome; wont goD. dont come; will go
7、4. _ you go to the supermarket at 7 , you can buy a lot of cheap food.A. IfB. UnlessC. WhetherD. When5. I wont get to the partyon time _ I catch the firsttrainA.IfB. UnlessC. WhetherD. Whent rainingtomorrow morning.6. -Shall we go on a picnic this weekend?-Good idea! Unless it _.A. rainsB. doesnt ra
8、inC. rainD. wont rain7. -Can I change the jacket for another one _ it doesnt fit me well?- Of course.A. unlessB. ifC. thatD. though8. Nobody can learn maths wellhe works hard on it.A ifB unlessC thoughtD however9. If fishaway from water, theydie.A are taking, wontB are taken, willC are being taken, willD take, wont10. Each studentcan ask teachersfor help ifhehowto work out the problem.A will knowB wont knowC dont knowD doesnt know