状语从句---条件状语从句
（1）if 和unless 引导的条件状语从句。 if 表示正面的条件，意为“如果”；unless(=if---not )表示反面的条件，意为“除非，如果不”。 Eg. ①If you had come a few minutes earlier, you would have met him. ②I may not come to see you recently unless I can complete the project ahead of time.
(2)in case, on condition that, providing(that), provided(that), supposing (that), suppose(that )等词汇意思相近，意为“万一， 假设，假如，在---条件下”。
①In case there is a fire, what will we do first?
②Supposing/suppose(that)they refuse us, who else can we turn to for help?
?They agreed to lend us the car on condition that we returned it before the weekend.
典例 The company promised to give us a discount we pay in advice.
A. even if B.as if C. so that D. provided that (3)as long as (=so long as )引导语气强烈的条件状语从句，意为“只要”。
Eg. I don't mind where you go, as long as you're back before midnight. (4)在“祈使句+and/or/or else/otherwise+陈述句”句型中，祈使句在意义上相当于条件状语从句。
Eg.① Run faster and you will catch the bus. = ?Work hard, otherwise you will fail.
(5)if only”如果---就好了”和only if “只有”也可引导条件状语从句。 但是only if 置于句首时，主句用部分倒装。 Eg. If only I had a dog, I wouldn't be so lonely. Only if a teacher has given permission is a student allowed to leave the room.
复习时要掌握条件状语从句的四大考点：
（1）考查引导词。只要弄清楚上下文的语义关系，并掌握引导词的意思，就能准确快速地写出答案。
（2）考查时态。在含有条件状语从句的复合句中， 主句若用一般将来时，从句往往用一般现在时表示将来。
（3）考查条件句中的虚拟语气。条件句中的虚拟语气主要体现在if 型虚拟条件句和错综时间的条件句中。
①if 可引导真实的条件句，表示假设的情况有可能实现。 Eg. I will stay at home if it doesn't rain.
② if 引导虚拟条件句，表示假设的情况很难实现或与事实相反。 （1）与现在事实相反，从句谓语动词用过去时（did/were）, 主句谓语动词用would/should/could/might+do
（2）与过去事实相反，从句谓语动词用过去完成时（had done）,主句谓语动词用would/should/could/might +do
（3）与将来事实相反， 从句谓语动词用should do/did/were to do ,
主句谓语动词用would /should/could/might+do
Eg.① If I (be) ten years younger, I would start all over again.
②If you (warn)him of the danger, he would not have been seriously injured.
典例 （2014.北京）We back in the hotel now if you didn't lose the map.
A. are B. were C. will be D. would be
(2013.福建) --- Do you think George has passed the driving test ? ---- No. If so, he his car to our college yesterday.
A. would drive B. drove C. would have driven D. had driven 注意：在if 虚拟条件句中， 如果要省略if, 必须把从句中的had, were,或should 置于句首，构成部分倒装。
Eg. 【①】Were I you, I would find a chance to make up with him. 【②】Had you had a deep communication with your mother, she would have supported you .
【?】Should I have time, I would go and watch the football game. ?If 引导错综时间的条件句
在错综条件句中，条件从句和主句的谓语动词发生的时间背景不同，因此，条件从句和主句的谓语要根据谓语动作各自的时间背景选用不同的形式。
Eg. If I were you, I wouldn't have missed the film last night.
If he had followed the doctor's advice, he would recover now.
典例 （2013.天津）If he had spent more time practising speaking English before, he able to speak it much better now.
A. will be B. would be C. has been D. would have been ④含蓄条件句
含蓄条件句中没有if 引导的从句来表示虚拟条件， 其虚拟条件通常由without, but for, otherwise等引出或表示。 Eg. But for your help, we couldn't have succeeded. (=If it had not been for your help)
典例（2013.安徽）I to my cousin's birthday party last night, but I was not available.
A. went B. had gone C. would go D. would have gone (4) 省略形式
如果条件状语从句的主语和主句的主语一致或从句的主语是it,且从句的谓语中有be 动词， 可以把从句的主语和be动词一起省略。 另外还有一些省略后的固定短语， 如if possible, if necessary, if not（如果不是这样), if so, if any （如果有的话）等。 Practice:
填空题：（根据句意填写引导条件状语从句的连词）
1. （2014.湖南改编）You will never gain success you are fully devoted to your work.
2. (2013.重庆改编) we have enough evidence, we can't win the
case.
3. (2012.福建改编) It is hard for the Greek government to get over the present difficulties it gets more financial support from the European Union.
4. (2010.全国Ⅰ.改编) The little boy won't go to sleep his mother tells him a story. 选择题：
1. (2014.四川) I'll be out for some time. anything important happens, call me up immediately.
A. In case B. As if C.Even though D.Now that
2. (2012.江西) You can borrow my car you promise not to drive too fast.
A. unless B. even if C. in case D. as long as
3.(2012辽宁)Leave your key with your neighbor you lock yourself out one day.
A. as long as B. even though C. in case D. as if
4.(2014.湖南) If Mr Dewey present, he would have offered any possible assistance to the people there.
A. were B. had been C. should be D. Was
5.(2014浙江) They were abroad during the months when we were carrying out the investigation, or they to our help.
6.(2014天津) the morning train, he would not bave been late for