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1、条件状语从句条件状语从句第1页预习：1.什么是条件状语从句？2.条件状语从句怎样与主句时态搭配？第2页条件状语从句条件状语从句经典例句：1.Ifyoustickapinintoaballoon,itbursts.2.Unlessyoukeepicecreaminafridge,itmelts.第3页一、什么是条件状语从句？一、什么是条件状语从句？在某种条件下，可能发生某事。而由在某种条件下，可能发生某事。而由if/unless引导表示条件句子，就叫条件状语引导表示条件句子，就叫条件状语从句。从句。eg:If you get up early,you will catch the bus.If
2、you put wood into water,it floats.第4页二、时态二、时态1当主句和从句所表示是当主句和从句所表示是原理、客观真理、原理、客观真理、规则时规则时，主句主句是是普通现在时普通现在时（包含祈使（包含祈使句和含有情态动词句和含有情态动词can/may/must等），等），从句从句也要用也要用普通现在时普通现在时。比如：比如：1)If you put a piece of paper into water,it gets wet假如你把一张纸放进水中，它假如你把一张纸放进水中，它会变湿。会变湿。(原理原理)第5页 2)Be careful if you cross th
3、e road.(祈使句祈使句)3)You must see the doctor if you are ill.(含有情态动词）含有情态动词）第6页2.在在if条件状语从句中，假如从句谈论是一个条件状语从句中，假如从句谈论是一个可能发生事实及其产生相关结果，可能发生事实及其产生相关结果，主句主句用用普普通未来时通未来时，从句从句用用普通现在时普通现在时。eg:1)If it rains tomorrow,we will not go to the zoo.2)If you go to bed earlier,you wont feel tired in the morning.第7页3.假如从
4、句用现在进行时或现在完成时，主假如从句用现在进行时或现在完成时，主句需用普通未来时。句需用普通未来时。1）IfyouarelookingforPeteryoullfindhimupstairs.假如你是在找彼得，上楼就会找到他。2）IfyouhavefinisheddinnerIllaskthewaiterforthebill.假如你吃完了，我就叫服务生来算账。第8页三、条件状语在句中位置三、条件状语在句中位置 大多数情况下，大多数情况下，if/unless从句既能够放在从句既能够放在主句之前也能够放在主句之后。当从句置于主句之前也能够放在主句之后。当从句置于主句之前时，惯用逗号与主句隔开。主
5、句之前时，惯用逗号与主句隔开。It floats if you put wood into water.=If you put wood into water,it floats.第9页 四四、转换、转换 1、当主语是当主语是you时时,if引导条件状语从句可与引导条件状语从句可与“祈使句祈使句+andor+简单句简单句”进行句型转换。进行句型转换。and表示句意顺承；表示句意顺承；or表示转折，意为表示转折，意为“不不然然”。比如：比如：Take care,or youll fall off the tree.小心，不然你会从树上掉下来。小心，不然你会从树上掉下来。=If you dont
6、take care,youll fall off the tree.第10页2.unless也可引导条件状语从句，相当于也可引导条件状语从句，相当于if.not，意思是，意思是“假如不、除非假如不、除非”。比如：比如：You will fail in Math unless you work harder.=You will fail in Math if you dont work harder.你要是不再加把劲儿，数学考试就不及格了你要是不再加把劲儿，数学考试就不及格了。第11页五、拓展五、拓展1.if从句还能够从句还能够表示不可实现条件或根本不可表示不可实现条件或根本不可能存在条件能存在
7、条件，也就是一个虚拟条件或假设，也就是一个虚拟条件或假设，从句从句多用普通过去时或过去完成时多用普通过去时或过去完成时，主，主句则句则用虚拟语气用虚拟语气。1)If I were you,I would invite him to the party.2)I would have arrived much earlier if I had not been caught in the traffic.第12页2.if表示表示“是否是否”时引导宾语从句，意思同时引导宾语从句，意思同whether.I dont know if he can come.If he comes,I ll tell y
8、ou at once.第13页一、用括号内单词适当形式填空1.Ifyou_(feel)tired,you_(have)tohavearest.2.Where_he_(see)thefilmifhe_(have)time?3.Ifthere_(be)fewertrees,there_(be)morepollution.4.He_(dress)morecasuallyifhe_(notwork)onweekends.5.IfMarcia_(live)alone,she_(keep)apetparrot.第14页6.If you _(need)the instructions in English,
9、go to our website.7.If the green light_(not be)on,we must wait for one minute.8.I dont know if he_(come)tomorrow.9.If you dont put fish back to water,it_(die).10.Dont go out tomorrow if it _(rain).第15页二、同义句转换二、同义句转换1.Play some sports,and youll be healthy._ _ play some sports,youll be healthy.2.If yo
10、u study hard,you will catch up with your classmates._ you study hard,you wont catch up with your classmates.3.Fish will die without water.Fish will die _ there is no water.第16页4.Dont stay up later,or wont be sleepy tomorrow._ you _ stay up late,you wont be sleepy tomorrow.5.I will come to see you un
11、less I am too busy._ I am _ too busy,I will come to see you.第17页三三 依据汉语提醒完成句子依据汉语提醒完成句子1.假如我有时间话，我就会去帮你。假如我有时间话，我就会去帮你。If I _ _,I _ _ you with it.2.假如明天不下雨，我们就去徒步旅行。假如明天不下雨，我们就去徒步旅行。If it _ _ tomorrow,well go hiking.3.我们没有些人能赶上汤姆，除非他不跑。我们没有些人能赶上汤姆，除非他不跑。None of us can _ _ _ Tom _ he doest run.第18页4.
12、他不会迟到，除非他生病。他不会迟到，除非他生病。He _ _ late _ he _ ill.5.假如你看见汤姆，叫他来我办公室。假如你看见汤姆，叫他来我办公室。_ Tom to come to my office _ you _ him.第19页Good morning,ladies and gentlemen!May I have your attention,please?Im a volunteer and Im glad to tell you something about protecting the beaches in Shenzhen.As we know,beaches
13、are great places for us to travel and relax.In order to protect the beaches,our government has made some strict rules.However,some citizens dont understand it.第20页 In my opinion,these strict rules can help us create a better beach environment.The beaches will be cleaner and more beautiful if each to
14、urist can realize the imoportance of protecting them.第21页 So I hope all of us will try to follow these:Never throw rubbish everywhere.Dont step on the grass or pick flowers near the beach.In a word,beaches are an important part of our living environment;we all need to try our best to protect them.（小结）（小结）Thank you for your listening.Have a nice weekend!第22页