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1、grammar,Conditional clauses,条件状语从句,引导条件状语从句最常用的连词是if，常见的if条件状语从句表示在某条件下，某事很可能发生 If you ask him，he will help you如果你请他帮忙，他会帮你的。If you fail in the exam，you will let him down如果你考试不及格，你会让他失望的。,如果你作业做完了就可以回家了。If you have finished the homework，you can go home.,If 从句（一般现在时），主句（一般现在时）,表示科学常识，说明，经常性的动作，倾向 自动会
2、发生的事 1.If water is heated,it turns to steam.2.If people dont get enough sleep,their thinking ability is reduced.3.If I need a haircut,I usually go to the barbers near where I live.4.People often dont go out on Sundays if it rains.,2表示将来的可能性，能力，允诺，命令，要求，请求，建议时，运用“主将从现”的原则。,1.If I get the job,Ill buy
3、a mobile phone.2.If my homework is difficult,Ill ask Helen to help me.3.If I have time this afternoon,Ill go to the barbers to get a haircut.,那么，除了if之外，是否还有其他连词可以引导条件状语从句呢,回答是肯定的。不仅有，还有很多。这些词由于出现的频率小，且用法较复杂一些，所以不如if为大家所熟知罢了。下面就这些词的用法做一介绍。,1unless 除非；若不；如果不；除非在时候,1.You will fail to arrive there in ti
4、me unless you start earlier如果你不早点动身，你就不能及时赶到那儿。2.Unless bad weather stops me，I go for a walk every morning除非天气不好，我每天早晨都要去散步。3.I wont loan you unless you are in extreme need of money若不是你急需用钱，我不会借钱给你的。,2on condition that只有在条件下，以为条件,on condition that引导的条件从句是主句中事件发生的前提条件或唯一条件。I can tell you the truth on
5、 condition that you promise to keep a secret我可以告诉你真相，条件是你答应保守秘密。You can pass the custom on condition that we have checked your luggage你可以通过海关，但条件是我们得检查完你的行李。,3supposing(that)conj假若，倘若,supposing 引导的从句表示一种假设条件。通常在句首 Supposing it rains，shall we continue the sports meeting？倘若下雨，我们的运动会还会继续进行吗？Supposing t
6、he stocks of food run out，what shall we do？假若储备的食品都吃光了，我们怎么办呢？,4provided that./providing(that)conj假若,provided/providing（that）从句表示一种假设条件。He will sign the contract provided(that)we offer more favorable terms如果我们提出更优惠的条件，他就会在合同上签字。He wont be against us in the meeting providing(that)we ask for his advic
7、e in advance如果我们提前征求一下他的意见，他就不在会上反对我们。,5.as(so)long as.“只要，就”表示 一种前提条件,Youll succeed as(so)long as(if only)you try hard.只要你努力，你就会成功。,but for+短语，要不是,6.But for the rain，we should have a pleasant journey要不是下雨，我们的旅行肯定很愉快。=If it didnt rain,we should have a pleasant journey.But for your help,we should not
8、 have finished the task in time要不是你帮忙，我们肯定不能及时完成任务。=If you hadnt helped us,we should not have finished the task in time.,Without.+短语，如果没有.,7.Without water,there would be no life on earth at all如果没有水，地球上就不会有生命。=If there were no water,there would be no life on earth at all.,If+虚拟条件句，,1.If I were you，I would invite him to the party如果我是你，我会邀请他参加聚会。I would have arrived much earlier if I had not been caught in the traffic要不是交通堵塞，我本会来得早一些。If it should be true,it would be silly to argue any longer.,
