动词的时态和语态.docVIP

一、情态动词的用法 1、can and could Eg1 electricity can drive motors.（） Eg2. you can borrow ten books at a time from the library.（） Eg3. he could swim across the river.（） Eg4. there can be no knowledge apart from practice.（） Eg5. could you help me lift the plate?（） 注释：could is can的过去时，除具有can 的功能外，还可以用来比较委婉，客气地提出问题或看法。 2、may and might Eg1. may /might I use this instrument to measure?（） Eg2. you may use my bike.（） Eg3. he may come back late this evening.（） Eg4. may you have a merry Christmas!!（） Eg5. a man’s ability may be great or small.（） Eg6. cables are usually laid underground that their life may be prolonged.（） 注释：might是may的过去时，在表示“可能”时，may 和 might是可以换用的，但might表示可能性较小或者表示婉转语气，如： Tom may lend you the money.（） Tom might lend you the money .（） Might I ask you a question?（） 3、must 和have to Eg1. we must have a plan before we doing any work.（） Eg2. she has to do it herself .she has got no one to help her.（） Eg3. this conclusion must be correct.（） Eg4. since air has weight ,it must press down on the surface of the earth.（） Eg5. you had to set your house in order yesterday.（） Eg6. tomorrow you will have to set to learning English.（） 注释：（1）eg1,eg2中have to 强调客观条件促使不得不做某事，must表示主观认为有必要做某事。 （2）eg3,eg4中，must用于推测，主要用于肯定句中，其否定形式用can’t，表示不可能，如： If he didn’t leave here at 4’clock,he can’ （3）eg5,eg6中，have to可用于过去时和将来时，而must一般只用于现在时。 4、need and dare Eg1. I need only add a few words. =I only need to add a few words. Eg2. he need never know. =he never needs to know. Eg3. she dare not go out night. =she doesn’t dare to go out at night . Eg4. you are mistaken ,I dare say. 注释：need 和dare既可作情态动词，又可作行为动词，两者可进行转换，dare一般只用于疑问句、否定句或条件句中，在肯定句中常以“I dare say” 的形式出现。 5、shall and will Eg1. I will go if you wish.() Eg2. you naughty boy! You shall get what you deserve.() Eg3. whatever you may say ,he shall go.() Eg4. whatever you may say, he will go.() Eg5. will you give her the letter?() Eg6.