Unit 5 It must belong to you.It must be Nings. It has her name on it.It could be Alis. She studies French.It might belong to Alice. She plays the guitar.It cant be Johns. Its much too small for him.must 很可能很可能, 一定一定, 肯定肯定,might 也许；或许；可能也许；或许；可能could 能，能， 可能可能cant 不能不能, 不会不会情态动词情态动词v情态动词：本身有词义，表示说话人的语气或情态，但词义不完全，只能与不带to的动词不定式连用，后面跟动词原形，一起（ought等除外）构成谓语。mustv表示推测，多用于肯定句。v在肯定句中must+动词原形表示对现在和将来的判断、推测。 You must be very tired.vMust+ have +p.p. 表示过去的判断、推测。vShe wasnt home last night. She must have gone to her mothers.v表示必须要做的事。(主观）v表示义务、命令或必要。必须, 应当 We must keep our word. 我们必须遵守诺言。v表示不可避免性或肯定性。必然要, 必定会 Man must die. 人必有一死。v表示与说话人愿望相反及不耐烦。偏要 Why must it rain on Sunday? 为什么偏要在星期天下雨？!vMust的否定： neednt 或 dont have tovMustnt 千万不能，一定不要，表示禁止行为。vYou mustnt tell anybody about this - its a secret.v这件事你不能告诉任何人 - 这是一个秘密。might mightntv为 may 的过去式,在陈述句中表示一般的可能性。有时用might代替may，使语气婉转，表达可能性时也远不如may把握性大。可以, 或许; 可能 I said that it might rain. 我说过可能会下雨。v表示现在或将来不太确实的可能性。也许, 或许; 可能 Im afraid it might rain tonight. 我看今晚可能要下雨。v表示对过去事实的推测might+have+p.p. He might have been Tibet before. 他以前可能去过西藏。v用于疑问和建议时语气比 may 更加委婉,谦虚。可以vMight I ask a question? 我是不是可以提个问题我是不是可以提个问题? ?v表示愿望、祝愿、请求表示愿望、祝愿、请求, , 嘱咐。请嘱咐。请, , 愿愿, , 还是还是.好好 You might at least apologize. 你至少应该道个歉吧。你至少应该道个歉吧。v用于虚构条件句中。会用于虚构条件句中。会; ; 可能可能 I would go if I might. 如我能去我就去。如我能去我就去。Could couldntv表示可能性。能，表示可能性。能， 可能，可能， 可以可以 You could do better.You could do better.v用于委婉语气。能，用于委婉语气。能， 可以可以 Could you do Could you do sthsth. for me?. for me?v用于虚拟语气中，用于虚拟语气中， 表示相反的假设。能，表示相反的假设。能， 本来本来可以可以 I could come tomorrow if you like.I could come tomorrow if you like.v在虚拟条件句中构成谓语。在虚拟条件句中构成谓语。 I would help you if I could.I would help you if I could.cantvcant =can not 不能, 不会 表示否定。 No, thats cant be ture.belong tov属于；为的财产 That book belongs to me. 那本书属于我。v为的一员 What club do you belong to? 你是哪个俱乐部的?v和有关联动词的语态动词的语态英语中有主动和被动两种语态。前者以动作的执行者充当主语，后者以动作的承受者 (即宾语) 充当主语。由于只有及物动词才有宾语，因此只能是及物动词才有被动语态形式。被动语态以助动词be加上动词的过去分词构成，如：We speak English. (主动语态)English is spoken. (被动语态)有时为了表明动作的执行者，可在被动语态有时为了表明动作的执行者，可在被动语态句型中加上介词句型中加上介词byby引导的短语，如：引导的短语，如：The glass was broken by the cat yesterday. .由于动词由于动词be在不同时态中有不同形式，在不同时态中有不同形式，因此被动语态在各种时态中也有不同的结构。因此被动语态在各种时态中也有不同的结构。一般现在时由一般现在时由am/are/is加上过去分词构成，加上过去分词构成，如：如：Football is played all over the world.The rooms are cleaned every day.一般过去时由一般过去时由was/were加上过去分词构成，加上过去分词构成，如：如：The telephone was invented by Thomas Edison.A lot of people were hurt in the traffic accident.一般将来时由一般将来时由will be加上过去分词构成，加上过去分词构成，其中其中will也可用情态动词替换，如：也可用情态动词替换，如：The work will be finished tomorrow morning.This problem can be worked out in another way.Something must be done to stop the wind from blowing the earth away.现在完成时由have/has been加上过去分词构成，如：A lot has been talked about the protection of our environment.Many ways have been tried to help the sick boy.现在进行时由am/are/is being加上过去分词构成，如：A new bridge is being built on the river.All the factories are being moved outof the city.虚拟语气虚拟语气 句子假设的情况如果是完全不存在的句子假设的情况如果是完全不存在的（与现在或过去的事实相反），或者实现（与现在或过去的事实相反），或者实现的可能性很小（与将来的事实可能相反的可能性很小（与将来的事实可能相反），），这种句子叫做虚拟条件句，它的谓语动词这种句子叫做虚拟条件句，它的谓语动词用虚拟语气。用虚拟语气。虚拟语气在条件句中的用法有三种情况：虚拟语气在条件句中的用法有三种情况： 1.表示与现在事实相反的情况时，条件表示与现在事实相反的情况时，条件从句的动词用一般过去式（从句的动词用一般过去式（be的的过去式用过去式用were或或was），），主句的动词用主句的动词用would(should,could或或might)加加动词原形。例如：动词原形。例如：The little girl said,”If I were a president, I would do a lot of things for the people.”情况不可能发生。情况不可能发生。比较：比较：Bush said,” If I am the president, I will do a lot of things for the people.”他自他自认为情况很有可能发生。认为情况很有可能发生。If I were invited, Id go to the dinner party.(Fact: Im not invited, so I wont go.)If I had time, I would(should)go with you.(Fact: I am very busy, so I cantgo with you.)If she knew about it now, she would come.(Fact: She doesnt know about it.)If they did not water the flowers,the flowers would(could) not growso well.(Fact: They water the flowers everyday, so the flowers growwell.)2. 表示与过去事实相反时，表示与过去事实相反时，条件条件从句的动词用从句的动词用hadhad加加过去分词过去分词，主句的动词主句的动词用用would(should, couldwould(should, could或或might)might)加加havehave和和过去分词。例如：过去分词。例如：If he had come here yesterday, I shouldIf he had come here yesterday, I shouldhave told him.have told him.(Fact: He did not come and so I did not(Fact: He did not come and so I did nottell him.)tell him.)以下两种情况不讲以下两种情况不讲3. 表示与将来事实很可能相反的情况表示与将来事实很可能相反的情况时时, ,条件从句的动词条件从句的动词-(1)(1)过去式过去式( (即与上述情况即与上述情况1 1 相同相同) ) (2)(2)或用或用should +should +动词原形动词原形, ,(3)(3)或用或用were to+were to+动词原形动词原形; ;主句的动词用主句的动词用would(should, couldwould(should, could或或might)might)加动词原形。从句中这三种情况加动词原形。从句中这三种情况都是表示不大可能实现的假想情况都是表示不大可能实现的假想情况; ;不可能实现的程度不完全一样不可能实现的程度不完全一样. .第第(1)(1)种结构种结构( (过去式过去式) )所表示的情况所表示的情况, ,实现实现的可能性较大的可能性较大; ;第第(2)(2)种结构种结构(should+ should +(should+ should +动词动词原形原形) )所表示的情况所表示的情况, ,实现的可能性较小实现的可能性较小; ;第第(3)(3)种结构种结构(were to+(were to+动词原形动词原形) )所表示的所表示的情况情况, ,实现的可能性最小实现的可能性最小. . 例如：例如：If heIf he came came tomorrow, he would find me tomorrow, he would find me in my office.in my office.( (他他来不来没有什么把握来不来没有什么把握.).)If it If it should (happen to) rainshould (happen to) rain this afternoon, this afternoon,the football match would be put off.the football match would be put off.( (下雨的可能性不大下雨的可能性不大) )If you If you were towere to fail to catch the train, you fail to catch the train, youmight take the bus.might take the bus.( (事实上事实上, ,赶不上火车的可能性很小赶不上火车的可能性很小) )