if和unless區(qū)別和練習(xí)

1、Chapter1語 法If和unless引導(dǎo)的條件狀語從句我們用if引導(dǎo)的條件狀語從句來討論可能的條件以及該條件成立時(shí)可能的結(jié)果。一.學(xué)習(xí)if引導(dǎo)的條件狀語從句的用法，我們可先從如下的口訣入手：If條件句不一般，幾個(gè)要點(diǎn)記心問；條件句，放在前，逗號(hào)要句中間條件句表可能，主句多用將來時(shí)；條件旬表事實(shí)，主句常用現(xiàn)在時(shí)。We .can, walk .thereif we can ' t find a b她果我們找不到公車，也能走路去那里主句條件狀語從句If it rains tomorrow, we .will .not. go . to. the . zoo.如果明天下雨，我們就不去動(dòng)物園

2、條件狀語從句主句What w川 you go if you find someone in danger?主句條件狀語從句如果你發(fā)現(xiàn)某人有危險(xiǎn)，你會(huì)怎么做？If條件句有不同的類型，簡(jiǎn)述如下：1 .用if條件句表達(dá)客觀真理或普通現(xiàn)象If條件句用于表達(dá)客觀真理或普通現(xiàn)象時(shí)，主，從句時(shí)態(tài)均用一般現(xiàn)在 時(shí)，如：Eg. If you freeze water, it turns into ice.A fish dies if you take it out of water.2 .用if條件句表小將來可能發(fā)生的事情在表示將來可能發(fā)生的事情的if條件句中，主句用一般將來時(shí)，而if從句用一般現(xiàn)在時(shí)表示將來的

3、時(shí)間，即 主將從現(xiàn)Eg. If I like the house, I will buy it.如果我喜歡這房子，我就會(huì)把它買下I will tell her if I see her.如果我見到她，我就會(huì)告訴她。主句中的will也可以用情態(tài)動(dòng)詞 can, may或might等代替。如：Eg. If they are friendly, I might invite them to the party.如果他們很友善，我可能會(huì)請(qǐng)他們?nèi)⒓泳蹠?huì)If we hurry now, we can stop for coffee later. 如果我們現(xiàn)在抓緊時(shí)間，就可以稍后去喝咖啡注意：在條件句中，主

4、句部分只能使用動(dòng)詞will 的一般將來時(shí)，不能使用be going to的結(jié)構(gòu)二 . Unless 的條件句表示在特定條件下，才決定做或不做一件事，中文用的連接詞一般是 “除非” 和 “否則” 。如：除非刮臺(tái)風(fēng)，否則演唱會(huì)將如期進(jìn)行。在英語中，我們可以用unless表達(dá)這個(gè)意思, 相當(dāng)于if not。以這個(gè)句子為例：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

5、on singing unless she is told to stop.她會(huì)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（否則）來做同義句轉(zhuǎn)換t know the answer. t know the answer.t know the answer.Unless you listen carefully, you won= if you don t listen carefully, you won= you should listen carefully, or you won深圳中

6、考題：1. If I his phone number, I will tell you.A. findB. found C. will findD. have found2. We will go camping if it tomorrow.A. Won t rain B. didn t rain C. doesn t rain D. isn t raining3. I m waiting for my friend. If he , I swimming alone.A. doesn t come; will goB. won t come; will gocome; won t goD

7、. don t come; will go4. you go to the supermarket at 7 , you can buy a lot of cheap food.A. IfB. UnlessC. Whether D. When5. I won t get to the party on time I catch the first train tomorrow morning.A. IfB. UnlessC. Whether D. When6.Shall we go on a picnic this weekend?Good idea! Unless it.A. rains B

8、. doesn ' t rain C. rainD. won ' t rain7. Can I change the jacket for another one it doesn' t fit me well?Of course.A. unless B. ifC. that D. though8. Nobody can learn maths well he works hard on it.A if B unless C thought D however9. If fish away from water, they die.A are taking, won &

9、#39; t B are taken, willC are being taken, will D take, won ' t10. Each student can ask teachers for help if hehow to work out the problem.A will know B won' t know C don ' t know D doesn ' t know練習(xí)：A woman should never be seen eating or drinking, unless it be lobster salad and Champ

10、agne, the only true feminine and becoming viands.Lord ByronI don't feel right unless I have a sport to play or at least a way to work up a sweat.Hank AaronNo great poetry, of whatever kind, is conceivable unless the subject has become integrated with the poet's mind and mood. Lascelles Aberc

11、rombieI'm not going to just say nice things about everybody unless I mean it. F. MurrayAbrahamUnless you're willing to have a go, fail miserably, and have another go, success won't happen. Phillip Adams1. If I you, I very happy.A. were, would beB. am, shall beC. were, shall beD. am, woul

12、d be2. If he had not lost his money, he the piano last week.C. could have bought D. bought3. I known it, I should have told him.A. Have B. Had C. Having D. If4. the clouds, you would find the airplane in the sky easily.A. Were it not for B. If it had not been forC. If it were not D. Had it not been

13、for5. If I had known that, I _ so.A. wouldn t do B. won t doC. didn t do D. wouldn t have done6. If it _ so hard, we d go to town.A. isn t raining B. weren t rainingC. doesn t rain D. isn t going to rain1 .答案A 2 答案 C 3.答案 B 4.答案A 5.答案D 6.答案B7. He you if you to see him that afternoon.A. might tell, w

14、ere goingB. told, were goingC. might have told, had goneD. should tell, went8. If you had started sooner, you there.A. may have gotB. might have gotC. shall have gotD. must have got9. If we were to be 2oo years old, we everything.A. will change B. can changeC. could changeD. shall change10. I don t

15、think that I shall failt, ibf uI _ I would try again.A. failB. would failC. should failD. had failed11. If you to see Mary, what would you tell her?D. wereC. must12. If the train leaves at half past ten, there no time to lose.A. wouldB. is C. willD. has7.答案C8.答案B9.答案C 10.答案 C 11.答案 D 12.答案Bunless&qu

16、ot;除非，如果不” （=if - not） 例句 wI shall go tomorrow unless it rains. 如果不下雨，我明天去。-Shall Tom go and play football?-Not unless he has finished his homework.除非他完成作業(yè)，否則不能出去。I won ' t go unless he comes to invite me除非他本人來邀請(qǐng)我，不然我是不會(huì)去 的。I won t attend his birthday party unless invited （=unless I am invited）. 除非被邀請(qǐng)，否則我不去參加的生日晚會(huì)。1. The men will have to wait all day the doctor works faster（. 2001 北京春季）A.