高考英语：情态动词与虚拟语气.doc

语法学案：　情态动词和虚拟语气考点一 情态动词的基本用法1．can (1)表示能力。需注意的是，could表示过去一般的能力，而was/were able to表示有能力而且成功地做成了某事。 However great the difficulties may be，we can overcome them. The fire spread through the building very quickly，but everyone was able to get (2)表示理论上的可能性，意为“有时候可能会”。 Everything can happen；everything is possible and probable. (3)表示请求和允许。在问句中，could比can语气要委婉；但答语中要用can表示直截了当。—Could I use your cell phone? —Of course you can.(4)表示推测，常用于疑问句和否定句。 What can they be doing there?He cant be in the office，for the light has been turned off. [名师点津]　cant/can never be too.../cant/can never be...enough表示“再……也不为过”。You can never be too careful/careful enough while driving a car. 2．may (1)表示请求、允许，此时might比may的语气更委婉。 —May/Might I play basketball this afternoon? —No，you may not. (2)表示推测意为“可能、或许”。 We may go to the cinema tonight，but we are not sure yet. (3)用于祈使句中表示祝愿。 May you be happy every day and succeed in your work！祝你每天都过得开心且工作顺利！ [名师点津]　“may as well＋动词原形”意为“最好，倒不如”。 There is nothing to do，so I may as well go to bed. 3．must (1)表示“必须，应该”，must一般指主观，而have to指客观，表示“不得不”。 We must do everything step by step. I have to go now for Ive a meeting 15 minutes later. (2)表示推测，意为“一定会”，此时不能用于否定句。 He must be ill.He looks so pale. (3)mustnt表禁止，而have to的否定式意为“不必”。 Smoking mustnt be allowed in the office. —Must we hand in our exercise today? —No，you dont have to.[名师点津]　must表示偏执、固执，意为“偏要，硬要”。 If you must smoke，please go out. 4．shall (1)用于第一、三人称的疑问句中，用于征求对方的意见。 Shall I buy some picture books for the children? (2)用于第二、三人称的陈述句，表示说话人给对方的命令、警告、允诺或威胁；此外，当颁布法律、规定时也用shall。 You shall do as your teacher says. 5．should (1)表示劝告和建议，意为“应该”。此时ought to比should语气要强。 You should/ought to put more effort into your work. (2)表示预测可能性，意为“按道理应该会”。 He left Paris in the morning.So he should arrive here by supper time. [名师点津]　should表示惊讶、意外等情绪，意为“竟然”。 It is strange that such things should happen in our school. 6．will/would (1)表示意愿，可用于各种人称。 We will never give up working，whatever happens. (2)表示“请求，建议”，此时would比will更委婉。 Would you come in