1、Unit 3Teenagers should be allowed to choose their own clothes.Section AGrammar Focus I think students should be allowed to do homework with friends.Sixteen-year-olds should not be allowed to drive.Do you think sixteen-year-olds should be allowed to choose their own clothes?Look at these sentences.Gr
2、ammar Focus情态动词的被动语态情态动词的被动语态肯定句肯定句:主语主语+情态动词情态动词+be+be+动词过去分词动词过去分词否定句否定句:主语主语+情态动词情态动词+not+be+动词过去分词动词过去分词疑问句疑问句:情态动词情态动词+主语主语+be+be+动词过去分词动词过去分词Teenagers should be allowed to choose their own clothes.情态动词有四类：情态动词有四类：只做情态动词：只做情态动词：must,can(could),may(might)可做情态动词又可做实义动词：可做情态动词又可做实义动词：need,dare 具有情
3、态动词特征：具有情态动词特征：have(had,has)to,used to 情态动词表猜测情态动词表猜测 should have done,Teenagers should be allowed to choose their own clothes.青少年应该被允许选择他们自己的服装。青少年应该被允许选择他们自己的服装。Students should not be allowed to have part-time jobs.学生们不应该允许做兼职工作。学生们不应该允许做兼职工作。Can these books be taken out of the reading room?可以把这些书
4、带出阅览室吗？可以把这些书带出阅览室吗？When must the work be finished?这些工作必须什么时候完成？这些工作必须什么时候完成？1.Their work must _(finish)by four oclock.2.Your homework should _ (do)by yourself.3.These books mustnt _(take)out of the reading room.4.Should these food _(keep)dry?be finished be done be taken be kept 用所给词的适当形式填空。用所给词的适当形
5、式填空。翻译下列句子。翻译下列句子。1.青少年需要被好好地教育。青少年需要被好好地教育。_2.这辆小汽车不能修了。这辆小汽车不能修了。_3.这封信必须现在寄出去吗？这封信必须现在寄出去吗？_4.会议应该在哪举行？会议应该在哪举行？_Teenagers need to be educated well.This car cant be repaired.Must this letter be posted now?Where should the meeting be held?1.You must give back the dictionary before Friday.(改为被动语态改为
6、被动语态)The dictionary must _ _ back before Friday.2.He should be told about the meeting.(改为一改为一般疑问句般疑问句)_ he _ told about the meeting?按要求完成句子。按要求完成句子。(每空一词每空一词)be givenShould be3.The machine can be used for washing dishes.(对画线部分进行提问对画线部分进行提问)_ _ the machine _ used for?What can be【2011天津天津】39.Today a l
7、ot of information can _ online.A.receive B.be received C.is received D.receiving答案：答案：B 【解析】【解析】被动语态。今天有很多信息能在网上收到，被动语态。今天有很多信息能在网上收到，信息被收到要用被动语态。含有情态动词的被动语态信息被收到要用被动语态。含有情态动词的被动语态的构成：情态动词的构成：情态动词+be+过去分词。过去分词。【2011浙江金华浙江金华】22.Must we clean the classroom now?No,you neednt.It _ after school.A.may cle
8、an B.must clean C.need be cleaned D.can be cleaned答案：答案：D【解析】由句意可知【解析】由句意可知it指指classroom，it和和clean为被动为被动关系，所以用被动语态，含有情态动词的被动语态关系，所以用被动语态，含有情态动词的被动语态结构为结构为“情态动词情态动词+be+动词过去分词动词过去分词”。排除。排除A和和B。need意为意为“需要需要”，can意为意为“可能，可以可能，可以”。由句。由句意意“我们必须现在就打扫教室吗？我们必须现在就打扫教室吗？不，不必要。不，不必要。可以放学打扫可以放学打扫”可知。故选可知。故选D。【2011山东滨州山东滨州】Dear Erie,your room is too dirty,It should _(clean)right away.【2011无锡无锡】Food cannot _(keep)properly in a fridge at an unsuitable temperature.be cleanedbe kept
