高手们帮忙写写情态动词的英语语法!

高手们帮忙写写情态动词的英语语法!
高手们帮忙写写情态动词的英语语法!

高手们帮忙写写情态动词的英语语法!
情态动词 (Model Verbs) 又称为情态助动词 (Model Auxil-iaries).英语中助动词主要有两类：一是基本助动词,如have,do,be；二是情态助动词,如may,must,need等.情态动词与其他动词连用表示说话人的语气.情态动词可表达建议、要求、可能和意愿等.情态动词没有人称和数的变化.在大学英语四、六级考试中,情态动词部分重点测试以下内容：
（1）情态动词+行为动词完成式
（2）情态动词+行为动词进行式
（3）情态动词+行为动词完成进行式
（4）某些情态动词的特殊用法
一、情态动词+行为动词完成式
情态动词+行为动词完成式即“情态动词+ have + v-ed分词”,表示对过去行为或动作进行推测、评论或判断.
1.must have v-ed
must have v-ed 表示推测过去某事“一定”发生了.其否定形式为：can’t / couldn’t have v-ed,表示过去不可能发生某事.例如：
1）Since the ditch is full of water,it must have rained last night.
2）You couldn’t have met my grandmother.She died before you were born.
2.could have v-ed
could have v-ed 表示推测过去某动作“很可能”发生了.例如：
1）“The dictionary has disappeared.Who could have taken it?”
2）“Tom could have taken it.He was alone yesterday.”
3.may / might have v-ed
may / might have v-ed 表示推测过去某事“也许”发生了.may 比 might 表示的可能性在说话人看来稍大些.例如：
I can’t find my keys.I may / might have left them at the school yesterday.
4.ought to / should have v-ed 和 ought not to / shouldn’t have v-ed
ought to / should have v-ed 和 ought not to / shouldn’t have v-ed 用于对已发生的情况表示“责备”、“不满”,分别表示“本应该…”和“本不应该…”.例如：
1）With all the work finished,I should have gone to the party last night.
2）You ought not to make fun of him.He is not the one you laugh at but learn from.
5.needn’t have v-ed
needn’t have v-ed 表示过去做了某事,但没有做的必要,意为“本没必要…”.例如：
You needn’t have waken me up; I don’t have to go to work today.
注：表示推测过去某动作发生的可能性时,就表示的可能性程度而言,must最大,could其次,may更次之,might最小.例如：
“I wonder how Tom knew about your past.”
“He must / could / may / might have heard of it from Mary.”
二、情态动词+行为动词进行式
情态动词+行为动词进行式（即情态动词+ be + v-ing形式）,表示推测或评论某动作现在是否正在进行.例如：
1）He must be playing basketball in the room.
2）She may be staying at home.
三、情态动词+行为动词完成进行式
情态动词+行为动词完成进行式（即情态动词+ have been + v-ing 形式）,表示推测或评论过去某动作是否正在进行或一直在进行.例如：
1）They should have been meeting to discuss the problem.
2）He may / might have been buying stamps in the post office when you saw him.
四、某些情态动词的特殊用法
1.need
考试中主要测试 need 作情态动词与作实义动词的区别,对此,可参见表1.need 作情态动词时,后面跟不带to 的动词不定式,即 “need to”.通常用在疑问句和否定句中,表示询问是否有“必要”,其否定形式为needn’t,表示“不必”；疑问形式为 Need … do?极少用于肯定句.例如：
1）I don’t think we need turn the light on at that time.
2）Need you ride a bike to school?
情态动词need与实义动词need 在时态、肯定、否定结构上的对比见表1.
2.dare
考试中主要测试dare作情态动词和作实义动词的区别.
情态动词dare 与实义动词dare 在时态、肯定、否定、疑问结构上的对比见表2.
3.can 和 may
考试中主要测试can,may或could,might表示可能性的区别及对may构成的疑问句的回答.
时态 情态动词need 实义动词 need
现 You need (not) do You (don’t) need to do
在
时 He need (not) do He needs (doesn’t need) to do
过 You needed (didn’t need) to do
去
时 He needed (didn’t need) to do
将 You need (not) do You will (not) need to do
来
时 He need (not) do He will (not) need to do