条件状语从句课件

条件状语从句条件状语从句1条件状语从句1预习：1.什么是条件状语从句？2.条件状语从句如何与主句时态搭配？2预习：2条件状语从句条件状语从句经典例句：1.Ifyoustickapinintoaballoon,itbursts.2.Unlessyoukeepicecreaminafridge,itmelts.3条件状语从句3一、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引导的表示条件的句子，就叫条件引导的表示条件的句子，就叫条件状语从句。状语从句。eg:If you get up early,you will catch the bus.If you put wood into water,it floats.4一、什么是条件状语从句？4二、时态二、时态1当主句和从句所表示的是当主句和从句所表示的是原理、客观真理、原理、客观真理、规则时规则时，主句主句是是一般现在时一般现在时（包括祈使（包括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一般现在时一般现在时。例如：例如：1)If you put a piece of paper into water,it gets wet如果你把一张纸放进水中，它如果你把一张纸放进水中，它会变湿。会变湿。(原理原理)5二、时态5 2)Be careful if you cross the 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）62)Becarefulifyoucrossthe2.在在if条件状语从句中，如果从句谈论的是一条件状语从句中，如果从句谈论的是一个可能发生的事实及其产生的相关结果，个可能发生的事实及其产生的相关结果，主主句句用用一般将来时一般将来时，从句从句用用一般现在时一般现在时。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.72.在if条件状语从句中，如果从句谈论的是一个可能发生的事3.如果从句用现在进行时或现在完成时，主如果从句用现在进行时或现在完成时，主句需用一般将来时。句需用一般将来时。1）IfyouarelookingforPeteryoullfindhimupstairs.如果你是在找彼得，上楼就会找到他。2）IfyouhavefinisheddinnerIllaskthewaiterforthebill.如果你吃完了，我就叫服务生来算账。83.如果从句用现在进行时或现在完成时，主句需用一般将来时。三、条件状语在句中的位置三、条件状语在句中的位置 大多数情况下，大多数情况下，if/unless从句既可以放在从句既可以放在主句之前也可以放在主句之后。当从句置于主句之前也可以放在主句之后。当从句置于主句之前时，常用逗号与主句隔开。主句之前时，常用逗号与主句隔开。It floats if you put wood into water.=If you put wood into water,it floats.9三、条件状语在句中的位置9 四四、转换、转换 1、当主语是当主语是you时时,if引导的条件状语从句可引导的条件状语从句可与与“祈使句祈使句+andor+简单句简单句”进行句型转进行句型转换。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“否则否则”。例如：例如：Take care,or youll fall off the tree.小心，否则你会从树上掉下来。小心，否则你会从树上掉下来。=If you dont take care,youll fall off the tree.10四、转换102.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“如果不、除非如果不、除非”。例如：例如：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。112.unless也可引导条件状语从句，相当于if.五、拓展五、拓展1.if从句还可以从句还可以表示不可实现的条件或根本不表示不可实现的条件或根本不可能存在的条件可能存在的条件，也就是一种虚拟的条件或，也就是一种虚拟的条件或假设，从句假设，从句多用一般过去时或过去完成多用一般过去时或过去完成时时，主句则，主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.12五、拓展122.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 you at once.132.if表示“是否”时引导宾语从句，意思同whether.一、用括号内单词的适当形式填空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.14一、用括号内单词的适当形式填空146.If you _(need)the instructions in English,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).156.Ifyou_(need)theins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 you 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.16二、同义句转换164.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 unless I am too busy._ I am _ too busy,I will come to see you.174.Dontstayuplater,orwont三三 根据汉语提示完成句子根据汉语提示完成句子1.如果我有时间的话，我就会去帮你。如果我有时间的话，我就会去帮你。If I _ _,I _ _ you with it.2.如果明天不下雨，我们就去徒步旅行。如果明天不下雨，我们就去徒步旅行。If it _ _ tomorrow,well go hiking.3.我们没有人能赶上汤姆，除非他不跑。我们没有人能赶上汤姆，除非他不跑。None of us can _ _ _ Tom _ he doest run.18三根据汉语提示完成句子1.如果我有时间的话，我就会去帮你。4.他不会迟到的，除非他生病。他不会迟到的，除非他生病。He _ _ late _ he _ ill.5.如果你看见汤姆，叫他来我办公室。如果你看见汤姆，叫他来我办公室。_ Tom to come to my office _ you _ him.194.他不会迟到的，除非他生病。19Good 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 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.20Goodmorning,ladiesandgentl In my opinion,these strict rules can help us create a better beach environment.The beaches will be cleaner and more beautiful if each tourist can realize the imoportance of protecting them.21Inmyopinion,thesestri 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!22SoIhopeallofuswi