条件从句.ppt

1、条件句 (Conditionals),句子结构 IF + 分句 , 主句。 If Jim had a big note, he would lend you some money. 或者 主句 IF 分句 Jim would lend you some money if he had a big note. Note:主句使用then时，强调结果的产生取决于条件的实现。 If you want to pass CET 4 exam, then you have to spend more time on listening section. If Jim had a big note, the

2、n he would lend you some money.,句子类型,二、三类条件句,主从 句,构 成,时态,虚拟条件 从句,主 句,例 句,与现在事实相反的 假设,与过去事实相反的 假设,If + 主语 + 动词过去时 (be用 were),主语 + would/ should/could/ might + 动词 原形,If I had time, I would attend the meeting.,If + 主语 + had +过去分词,主语 + would/ should/could/ might + have + 过去分词,If you had taken my advice,

3、 youd have passed the exam.,零类条件句,句型 IF + 一般现在时（含现在完成时和现在进行时），一般现在时（含现在完成时和现在进行时）。 If you dont look after the puppy, it dies very quickly. If shes travelling abroad on business, she always phones her husband every evening. Prawns (大明虾) are very risky to eat if they havent been kept at the right temp

4、erature. Note: 主句或从句中也可使用can和may. Prawns can/may be very risky to eat if they havent been kept at the right temperature. If you can read English well, you (may) have another means to know the world.,使用零式条件句的条件,用来讲述任何时间或地点都可能发生、且不止一次的事件或情况或结果 If someone drinks wine or alcohol, he or she gets red spot

5、s on the skin. 用来讲述结果恒定的行为 If you put your hand on the hot iron, it is hurt badly. Note: 在上述两种情况下，if可由when替换。 When someone drinks wine or alcohol, he or she gets red spots on the skin. When you put your hand on the hot iron, it is hurt badly. If you press the green button, the game starts, and when

6、you click the red one, it stops.,一类条件句（可能条件句）,句型 If + 一般现在时（含现在完成时和现在进行时），will/wont + 不定式 If the museum charges for entry, a lot people wont be able to visit it. If you are coming to classroom tomorrow, you will need to bring the textbooks with you. Note: 主句或分句中都可使用can, may及should If the government

7、can keep the loyalty of the army, they may retain power. If the Spanish team continues to do well, they should win the World Cup.,一类条件句的用法,命令 If you get home late, dont wake us up! Dont forget to close the windows if you go out. Note: 此类用法中，主句使用祈使式。 意愿 Ill call the hotel if you dont have time. 建议 Sh

8、all we go out tomorrow if the weathers good? 警告 Ill call the police if you dont leave right now.,下列句子是否有误,If the weather will be good tomorrow, the family will have a picnic. Youll receive a certificate through the exam board if the result of the test will be negative. The company will start to give

9、 punishment if the workers wont stop the strike.,一类条件句的特殊用法,If分句通常不使用将来形式 If the weather is good tomorrow, the family will have a picnic. Youll receive a certificate through the exam board if the result of the test is negative. 如果will/wont表示“愿意或拒绝”，则可以在if分句中使用 The company will start to give punishme

10、nt if the workers wont stop the strike.,二、三类条件句,主从 句,构 成,时态,虚拟条件 从句,主 句,例 句,与现在事实相反的 假设,与过去事实相反的 假设,If + 主语 + 动词过去时 (be用 were),主语 + would/ should/could/ might + 动词 原形,If I had time, I would attend the meeting.,If + 主语 + had +过去分词,主语 + would/ should/could/ might + have + 过去分词,If you had taken my advi

11、ce, youd have passed the exam.,一类条件句？二类条件句？,选择一类条件句还是二类条件句，取决于说话人对事件发生可能性大小的评估。 If you phone the hotel in 5 minutes, you can get a cancellation. (认为打电话是可能） If you phoned the hotel in 5 minutes, you could get a cancellation.（认为打电话是不太可能的）,二类条件句的特殊用法,If分句中的be，通常体现为适用于各人称的虚拟式were，也可能为was. If the progamm

12、er was familiar with this language, it would be an easy job. If the progammer were familiar with this language, it would be an easy job. 但是在正式场合，还是不用was为好。,二类条件句的特殊用法,在美国英语中，would可以用于主从两个句子，但在英国英语中不能这样使用。 AmE: Such accident wouldnt happen if the police would be firmer with the driver. BrE: Such acci

13、dent wouldnt happen if the police were firmer with the driver.,二类条件句的特殊用法,二类条件状语从句中谓语动词部分是were+to do, 或是should +do时可把if 省略，把were， should提前, 引起倒装，使句子显得更加正式。 Were it not to rain tomorrow , we would have a picnic. Should it rain tomorrow , we would have a picnic. 助动词do或主动词不能至于主语之前 If the builders finis

14、hed the work to schedule, they would receive a bonus. Were the builders to finish the work to schedule, they would receive a bonus. Did the builders finished the work to schedule, they would receive a bonus. Finished the builders finished the work to schedule, they would receive a bonus. ,三类条件句的特殊用法

15、,美国英语中，if分句中使用would have是可能的；英国英语中，这种用法通常被认为是不正确。 AmE: If the play would have finished on time, we wouldnt have missed the train. BrE: If the play had finished on time, we wouldnt have missed the train. Had置于主语之前能使行文更具文采。 Had I not seen it with my own eyes, I would not have believed it. Had the film

16、 been released in the summer, it would not be have been so successful.,混合条件句二、三类混合条件句,句型：If 分句对现在的虚拟，主句对过去的虚拟。 If the island were still a tourist attraction, last weeks earthquake would have caused far more deaths. = The island is not a tourist attraction so the earthquake didnt cause a huge number

17、of deaths.,混合条件句三、二类混合条件句,句型：If 分句对过去的虚拟，主句对现在的虚拟。 If the weather had been finer, the crops would be growing still better. If you had followed the teachers advice, you wouldnt be in hospital.,If的替换式,否定条件 unless 必要条件 provided/providing (that), so/as long as, on (the) condition (that), but for 想像条件 Su

18、ppose/Supposing (that), What if, if only, in case, in case of 意外条件 even if 任选条件 whetheror not,否定条件,Unless常用于否定句，与ifnot或only if相似 Unless youve got a doctors medical permit, they wont allow you to go on the activity. = If you dont have a doctors medical permit, they wont allow you to go on the activit

19、y. I wouldnt be willing to help you out again unless you paid me. = I would help you again only if you paid me.,必要条件,provided/providing (that), so/as long as, on (the) condition (that), but for用于强调条件对结果的必要性，与only if相似。 The system will not have to be damaged provided that/on the condition that antivi

20、rus has been added. = The system will have to work efficiently only if antivirus has been added. provided/providing (that), so/as long as, on (the) condition (that)只能指对现在或将来的条件,不能指向过去的条件。 Well attend the meeting there, so long as you also arrange the catering. We would have attended the meeting ther

21、e, so long as you had arranged the catering. but for名词（短语）可以表示事情在过去发生的必要条件 But for the quick thinking of the driver, they all would have been badly injured in the accident.,想像条件,使用Suppose/Supposing (that), What if时，表示结果的主句可以被省略 Suppose/Supposing (that) he asked you to go to the cinema with him, (would you go?) Suppose you were a billionaire, (would you try it again?） What (will you do) if the money doesnt arrive on time? Wha