1、 2014高考英语宏志优化设计系列语法：牛津译林版专题6（情态动词讲解）语法专题六情态动词情态动词表示说话人的语气和情绪，本身词义不全，不能单独作谓语，后面必须与动词原形一起构成谓语。情态动词没有人称和数的变化，但有的情态动词有过去式。考点一can与could1表示能力，但could主要指过去的能力。表示“过去有能力成功做成某事”时通常用was/were able to。The little boy can speak two foreign languages.Could the girl read before she went to school?Everyone was able to
2、 escape when the fire broke out.2表示可能（理论上或是逻辑判断上，并不涉及此事真的发生），常译为“往往会，有时候可能会”，常用于肯定句中。Accidents can happen on rainy days.3表示请求和允许。在问句中could语气比can要委婉。You can go back home now.4表示惊异、怀疑、不相信等态度。主要用于否定句、疑问句或感叹句中。How can you be so careless?来源:5表示推测，常用于否定句和疑问句中，语气较强。He cant be in the classroom；the light is
3、not on.6cannot/never.too/enough.表示“再也不为过”。You can never be too careful when driving a car.7cannot but do sth./cannot help but do sth. /cannot choose but do sth.表示“不得不，只好做某事”。You cannot choose but go with me.考点二shall1用于第二、三人称的陈述句中，表示命令、许诺、警告、强制、威胁、决心等；此外，颁布法律、规定时也用shall。The new law shall come into ef
4、fect next month.2用于第一、三人称的疑问句中，表示说话人征求对方的意见或向对方指示。Shall the man standing outside have a try?考点三must1表示主观上的“必须，应该”，其否定形式mustnt表示禁止。对比：have to表示客观上的“不得不”，可用于各种时态。You must listen carefully in class.Students mustnt play with mobile phones in class.I had lost my key，so I had to wait outdoors.2表示“非要，偏要”做某
5、事，表达出说话者的一种不满情绪。Why must you be talking so loudly when others are sleeping?3表示对具体事情的推测，意为“一定，肯定”，语气较强，只用于肯定句中。He must come from America.考点四should 1表示义务，常译为“应该”，用于各种人称。Parents should take care of their babies.2表示预测可能性，译为“可能，（按道理）应该”，多指对未来合乎理想的情况或结果的一种期盼。Its nearly 8 oclock.He should be here at the mo
6、ment.3表示惊讶、意外等，常译为“竟然，居然”。I am surprised that you should speak ill of me.4用在if条件句中，表示可能性很小的一种虚拟语气，常译为“如果”。If I should see him，I would tell him the news.考点五will与would1表示意愿，用于各种人称的陈述句中。would常指过去的意愿。If you will read the book，Ill give it to you.2表示请求，用于疑问句。would语气较委婉。Will you close the window?3表示某种倾向或习惯
7、性动作，常译为“总是，惯于”。would 可表示过去反复发生的动作或某种倾向，后面接表示动作的动词，不能接表示状态的词。对比：used to表示过去的习惯动作或状态，强调现在已不存在。He would sit in the park which used to be a factory reading for hours.考点六may与might1表示请求、允许、许可，might比may语气委婉。You may use my bike.2表示推测，常用于陈述句中，语气比较弱，把握性不大。might语气比may还要弱。 He may go out.3may as well动词原形，意为“最好，倒
8、不如”。You may as well do it at once.4may well动词原形，意为“完全能，很可能”。Her appearance has changed so much that you may well not recognize at first sight.5may用于祈使句中，表示祝愿。May you return in safety.考点七need 与dare1二者都可以作为情态动词和行为动词。当作情态动词时，后面要接动词原形，通常用于否定句、疑问句和条件句中。用作行为动词时，其变化和一般的动词相同，有人称和数的变化，构成否定句和疑问句时要借助于助动词do，doe
9、s，did。dare用作行为动词，用于否定句和疑问句时，常省略后面的to。You neednt hurry；he needs to dress up.The little didnt dare（to）go out at night alone.2need作行为动词时，若主语为动作的承受者时用动词的主动形式表示被动意义或用不定式的被动形式。The house needs repairing.The house needs to be repaired.3I dare say为习惯说法，意为“我想，大概”。I dare say she dare not speak to her father in
10、 this manner.考点八情态动词表推测1can，may，must皆可用来表示推测。1）在肯定句中都可以用来表示可能性。在含义上“must”语气最肯定，“may”表示不太肯定的可能性，而can表示理论上的可能性。2）在否定句中只能用“can not”和“may not”。“cant”（不可能）语气比“may not”（可能不、也许不）更强。3）在疑问句中只能用“can”，不能用“may”和“must”。Accidents can happen on such snowy days.Look，there is some blood on the road；an accident must
11、have happened just now.But it cant have been Mike，for I saw him in the school.2should 与ought to 可以表示对未来情况的一种期盼，常译为“按理应当”。He should/ought to be here on timehe started early.考点九情态动词have done1could have done的疑问或否定形式表示对过去发生的行为表示怀疑或不肯定，其中couldnt have done 多用于语气强烈的否定，意为“过去不可能做过”。could have done在肯定句中表示“本来能
12、做但却没做”。The accident could have been avoided；the driver couldnt have slowed down.2may/might have done 表示对过去行为的推测，意为“可能做过”。might 所表示的可能性比较弱，此外might have done 还可表示“本可能做而实际上未做”，含有轻微的责备语气。You might have given him more help，though you were busy with your work.3must have done 表示对过去行为的推测，意为“一定，想必做过”，语气十分肯定。
13、It must have rained yesterday，as the ground is wet.4should/ought to have done 用于肯定句时，表示本该做某事，而实际上未做；用于否定句时，则表示不该做某事反而做了。You oughtnt to have been late for the meeting，as it was very important.5neednt have done 表示本来不必做某事而实际上却做了。I actually neednt have bought so much foodonly three people came.6had better have done 用于事后的建议，含轻微责备的口吻，意为“当时最好做了某事”。I had better have started earlier.
