C1P3-Language-八下英语第一课--上海教育出版社(课堂PPT).ppt

Language Chapter 11If you stick a pin into a balloon,it bursts.If you cool water,it turns into ice.2Conditional clauses with ifWe use if sentences to talk about possible actions and the results of those actions.An if sentence has two parts called clauses.Each clause contains a verb.In some if sentences,the tenses of both verbs are the same.In other if sentences,the tenses of both verbs are different.3条件状语从句，表示主句动作发生的条条件状语从句，表示主句动作发生的条件。由件。由if 引导的条件状语从句表示假如引导的条件状语从句表示假如有从句的动作发生就会有主句的动作发有从句的动作发生就会有主句的动作发生。如：生。如：Please call me if he is at home.假如他在家的话，请给我打电话。假如他在家的话，请给我打电话。If If 引导的条件状语从句引导的条件状语从句4If something dramatic happens,we usually remember it well.In these sentences,both verbs are in the same tense simple present.A If sentences:actions with definite results5In if sentences,the if clause can come first or second.When the if clause is first,there is always a comma after it.位置的变换：位置的变换：if引导的条件状语从句可引导的条件状语从句可以位于主句之前，也可以位于主句之后。以位于主句之前，也可以位于主句之后。当当if在前时，和主句之间必须用逗号隔在前时，和主句之间必须用逗号隔开。开。Things to remember6If you ask him,he will help you.（=He will help you if you ask him.）如果你请他帮忙如果你请他帮忙,他会帮你的。他会帮你的。If you cool water,it turns into ice.Water turns into ice if you cool it.7Possible actions1 If you take a fish out of water,2 If you cool water,3 If you boil water,4 If you heat metal,5 If you put wood into water,6 If you plant seeds in soil,7 If you drop a glass8 If you do not give plants water,Results a it melts.b it dies.c they grow.d it turns into ice.e they die.f it breaks.g it becomes steam.h it floats.A1 Match the possible actions with the results to make if sentences.8S1 What happens if you take a fish out of water?S2 It dies.S1 Are you sure?S2 Of course Im sure.If you take a fish out of water,it dies.A2 Work in pairs.Read the dialogue below and make similar dialogues about the sentences in A1on page 7.9A3 Complete these sentences with the words in brackets.Add commas where necessary.1.If you _ ice _ water.(turns/heat/it/into)2.A balloon _ it.(pin/a/if/stick/you/bursts/into/it)heat,it turns intobursts if you stick a pin into103 If you _ steam _water.(into/cool/turns/it)4 Metal _ it.(you/heat/melts/if)5 Wood _ water.(you/into/put/if/floats/it)6 A glass _ it.(drop/you/breaks/if)cool,it turns intomelts if you heat itfloats if you put it intobreaks if you drop 11If the telephone rings,I will answer it.If you get up late,you will be late for school.12时态时态“主将从现主将从现”主句一般将来时，从句一般现在时主句一般将来时，从句一般现在时1.如果你努力工作，你的梦想将会实现。如果你努力工作，你的梦想将会实现。If you work hard,your dream will come true.2.如果明天下雨，我不会出去散步。如果明天下雨，我不会出去散步。If it rains tomorrow,I wont go out for a walk.13时态：在条件状语从句中有一个基本规时态：在条件状语从句中有一个基本规章制度章制度主、从句时态呼应。即主、从句时态呼应。即主句主句用现在时，从句也用现在时用现在时，从句也用现在时；主句用过主句用过去时，从句也用过去的某种时态去时，从句也用过去的某种时态。具体。具体地讲，主句是一般现在时地讲，主句是一般现在时(包括祈使句和包括祈使句和含有情态动词含有情态动词can,may,must的陈述句等的陈述句等)，从句也用一般现在时。，从句也用一般现在时。You must see the doctor if you are ill.如果你生病了，必须去看医生。如果你生病了，必须去看医生。14In these sentences,the verb tenses are different.The verb in the if clause is in the simple present tense.The verb in the other clause is in the simple future tense.B If sentences:actions with possible results15如果主句是一般将来时，从句要用一般如果主句是一般将来时，从句要用一般现在时表示将来。如：现在时表示将来。如：If it rains tomorrow,we wont go on a picnic.如果明天下雨的话，我们就不去野餐了。如果明天下雨的话，我们就不去野餐了。16 一般将来时一般将来时 情态动词情态动词+原形原形 祈使句祈使句+if+一般现在时一般现在时171.I sometimes forget to take the right books to school.If you check your timetable every night,youll know which books to take.Williams sister is giving him advice about some of his problems.Choose the correct half-sentences from each box to complete her advice below.183.I sometimes forget which things to buy at the supermarketIf you write a shopping list,you will remember to get all the things.2.I was away from school today.I dont know what to do for homework.If you telephone your classmates,theyll tell you what homework to do.195.I dont know what this word means.If you look it up in the dictionary,youll find out its meaning.6.I tried hard to keep each picture in my mind,but failed at last.If you think about each picture for 10 to 20 seconds,itll stay in your mind better.4.I hate getting up!I always feel tired in the mornings.If you go to bed earlier,you wont feel tired in the mornings.20I wont go to the party unless Im invited.I wont apologize unlesshe apologizes first.21=The word unless means if not.Unless you keep ice cream in a fridge,it melts.If you do not keep ice cream in a fridge,it melts.unless22We can put clauses with unless at the beginning or end of a sentence.You will be late for schoolunless you leave now.if you dont leave now.Unless you leave now,If you dont leave now,you will be late for school.23C1 Join the sentences with unless.1.You improve your handwriting.You will lose marks in the examYou will lose marks in the exam unless you improve your handwriting.242.You will get a toothache.You clean your teeth regularly.3.We will play football tomorrow.It rains all day.You will get a toothache unless you clean your teeth regularly.We will play football tomorrow unless it rains all day.254.You close that window.Lots of mosquitoes will get in.5.The waiter comes soon.I shall leave this restaurant.Unless you close that window,lots of mosquitoes will get in.Unless the waiter comes soon,I shall leave this restaurant.26A 1 Well have a picnic2 Ill park the car at Peace Place3 Unless you want to watch something,4 Im going to buy a blouse for my mother5 Unless that noise stops soon,B a I shall telephone the police and complain about it.b unless I can think of a better idea for a present.c if the weather is fine tomorrow.d I am going to switch the television off now.e unless the car park there is full.C2 Match the half-sentences in Column A with the correct ones in Column B.27我们知道，引导条件状语从句最常用的我们知道，引导条件状语从句最常用的连词是连词是if，那么该如何使用它呢？请看：，那么该如何使用它呢？请看：一、结构一、结构if作作“如果如果”解，用来引导条件状语从解，用来引导条件状语从句，可放在主句前面或后面。例如：句，可放在主句前面或后面。例如：If I finish my report,I will be very happy.如果我完成报告，我将会很快乐。如果我完成报告，我将会很快乐。=I will be happy if I finish my report.要点小结要点小结28二、时态二、时态1.当谈论将来可能出现的情况时，主句用当谈论将来可能出现的情况时，主句用一般将来时，一般将来时，if从句用一般现在时。例如：从句用一般现在时。例如：If I am free,I will come to see you.如果我有空，我会来看你的。如果我有空，我会来看你的。2.当谈论可预测的、反复出现的情况当谈论可预测的、反复出现的情况时，主句和时，主句和if从句都用一般现在时，此时从句都用一般现在时，此时if相当于相当于when。这类句子通常表示不受时间。这类句子通常表示不受时间限制的自然法则，表示普遍真理和客观事限制的自然法则，表示普遍真理和客观事实。例如：实。例如：If you cool the water below zero,it turns into ice.如果你将水冷却到零度以如果你将水冷却到零度以下，它就会变成冰。下，它就会变成冰。29三、转换三、转换if从句和主句还可以由从句和主句还可以由“祈使句祈使句+and/or+简单句简单句”代替。其中代替。其中and表示句意顺承；表示句意顺承；or则意为则意为“否则否则”。例如：。例如：If you study hard,youll pass the exam.如果你刻苦学习，你就能通过考试。如果你刻苦学习，你就能通过考试。=Study hard,and youll pass the exam.If you dont hurry up,youll miss the train.如果你不快点儿你就赶不上火车了。如果你不快点儿，你就赶不上火车了。=Hurry up,or youll miss the train.30另外，另外，unless也可引导条件状语从句，也可引导条件状语从句，相当于相当于ifnot，意思是，意思是“如果不、除非如果不、除非”。例如：例如：Ill plant the flowers if it doesnt raintomorrow.如果明天不下雨，我就把花栽上。如果明天不下雨，我就把花栽上。=Ill plant the flowers unless it rainstomorrow.31321._ you have lots of money,you cant2.buy that house.A.If B.Because C.Unless D.Until2.You will fail the exam _ you dont study hard at it.OK,Ill try my best.A.and B.though C.but D.if单项选择单项选择333.Would you dance _ I asked you to dance with me?Certainly,Im willing to dance with you.A.if B.that C.though D.unless4.You wont learn English well _ you work hard.A.unless B.when C.if D.because345._ you dont go to bed earlier,you will feel tired next morning.A.Unless B.If C.Though D.Until6.I wont come to see you _ I am asked to.A.unless B.because C.if D.though357.May I play basketball,Dad?No,_ the weather is not so hot.A.unless B.if C.because D.when8.Would you like to go shopping with us tomorrow?Sure,_ I am busy.A.since B.unless C.when D.until369.If I find your raincoat,I _ you at once.A.tell B.told C.will tell D.have told10.Mrs.Black will come to help us with the celebration if she _ too busy tomorrow.A.is B.will be C.wont be D.isnt371.There will be a baseball match this 2.Sunday.Would you like to go with me?If I have time,I _ with you.(2008 新疆新疆)A.went B.will go C.go D.have watched382.Im waiting for my friend._,Ill go shopping alone.(2008 重庆重庆)A.If she comes B.If she will come C.If she doesnt come D.If she didnt come3.If I find his phone number,I _ you.(2009 北京北京)A.tell B.told C.will tell D.have told394.Youd better look up the new word in dictionary _ you dont know it.(2009 甘肃兰州甘肃兰州)A.if B.that C.though D.whether5.Dont talk loudly at the meeting.If you _,you will have to leave.(2009 浙江杭州浙江杭州)A.are B.do C.did D.can406.The art club is for members only.You cant go in _ you are a member.(2009 山东临沂山东临沂)A.unless B.because C.if D.though7.May I surf the Internet now?No,_ you have finished doing the dishes.(2009 浙江宁波浙江宁波)A.unless B.if C.because D.when41 1.We _(not wait)if they _2.(be)late.2.You _(lose)weight if you _(exercise)more.3.If a bee _(find)food,it _ (dance).4.If you _(put)wood into water,it _(float).wont waitarewill loseexercisefindsdancesputfloats用所给动词的正确时态填空。用所给动词的正确时态填空。42 1.Fish die.Theres no water or air._2.My baby sister never cries.She is hungry._ _3.I run every morning.Bad weather stops me._ _4.Im free this Sunday.I will visit you._If Im free this Sunday,I will visit you.Fish die if theres no water or air.My baby sister never cries unless she is hungry.I run every morning unless bad weather stops me.根据句意，选用根据句意，选用if if或或unlessunless连接句子。连接句子。431.Arrive on time,and you wont miss the plane._ _2.If you dont read the map carefully,you will be lost easily._ _ _If you arrive on time,you wont miss the plane.Read the map carefully,or you will be lost easily./You will be lost easily,unless you read the map carefully.改写同义句。改写同义句。443.If you try again,you may work out the problem._ _4.Hurry up,or you will miss the train._ _ _ _Try again,and you may work out the problem.If you dont hurry up,you will miss the train./You will miss the train unless you hurry up.4546