高中英语语法讲义——情态动词讲解

情态动词一．情态动词基本用法  1.❶ can和could，用在否定句和疑问句中,表示惊讶，用在否定句和疑问句中。        How could you do such a silly thing?❷cannot....too/enough 表示“无论...也不过分，越...越好”。 You can’t be too careful while driving? 2.may和might的区别    ❶表示许可、可能性、祝愿等意义，might比may更委婉。        A:给别人许可时。-May I play basketball this afternoon？        B:may/might as well+动原，“最好，倒不如”。❷may作“可以”讲时，疑问句回答用mustn’t/can’t表示禁止。 3. Must的用法❶表示禁止（用于否定中）   You mustn’t smoke in the bedroom.❷表示偏执、固执  -Could I have a word with you,mum? -Oh dear,if you must.❸must的否定回答        A:作必须讲时，疑问否定回答用don’t have to,needn’t        B：推测，一定讲时，回答用can’t.        C:mustn’t表禁止。          --May I use your car?  --No, you mustn’t./-Sorry,you’d better not.(委婉)注意：must强调内在职责，而have to 强调迫于外界压力，不得已而为之。 4 .shall的用法❶一、三人称征求意见时。请求对方时。Shall we begin our class?❷二，三人称陈述句中，说话人给对方的命令，警告、允诺或威胁。   You shall not get my support if you do such a thing. 5.will和would的区别❶自愿主动提出，如：意志、愿望或决心，would 过去，will not表示拒绝。   I have told him again and again to stop smoking,but he will not listen.❷will习惯性动作，有“总是”或“总要”之意。   Everything he will have a walk along this year.❸would过去习惯性动作，比used to 正式。   Last year our English teacher would sometimes tell us stories in English after   Class.❹used  to do 过去常，过去一直------只表示过去。         be used to do “用来”/be used to doing习惯于-----可表过、现或将。 6.dare表示敢于  情态：dare do      Dare you go home along？                 及物：dare to do   Do they dare to say what she thinks? 7.need用法   情态：need do               及物  need to do表示主动                    need doing 被动    My overcoats needs washing.   8.  must一定要,必须，应该（现在时）               have to 客观需要，能用于更多时态（过去或将来）       注意ought to 表示义务和责任“应该”，比should语气强。  You ought to take care of yourself.二．情态动词表推测用法情态动词适用场合对未来和现在推测对过去的推测(情态动词+完成体)may/might肯、否may/might domay/might have done可能做过，本应做而实际未做。can/could否、疑Could 肯can/could docan/could have done 本应做而实未做can’t have done 不肯能做过，语气强烈should肯、否、疑用来表示一种估计的情况，should doshould have done 本应做而未做shouldn’t have done 不应该做而做了ought to ought to doought to have doneought not to have doneneed need doneedn’t have done本来不必而实际已经发生了must肯定句must domust have done一定发生了  1.Sorry,I’m late,I might have turned off the alarm clock and go back again. 2.The accident could have been avoided. 3.You should have told me about it earlier. 4.You ought not to have said such words to your parents. 5.You needn’t have walked so quickly since time was enough. 6.He must have completed his work,otherwise,he wouldn’t be enjoying himself by seaside.