cg场景情态动词讲解及练习（选择＋阅读）
(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
初一数学有理数
（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
ncaa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，coul
d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
吉他分类
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
彩色素描 来
时 He need (not) do He will (not) need to do
脸部肌肉
句型 时态 动词
情态动词dare 实义动词 dare
经济法专业肯定句 现在时 dare to 少用 dare/dares to do
过去时 dare to 少用 dared to do
否定句 现在时 daren’t/dare not do do/does not dare (to) do
过去时 dared not do did not dare (to) do 其中造句
疑问句 现在时 Dare he do? Do you/Does he dear (to) do?
过去时 Dared he do? Did he dare (to) do
（1）can, could, may, might都可以表示可能性.can, could表示潜在的可能性或理论上或逻辑判断上存在的可能性；而may, might则表示事实上的可能性。此外，can还具有“有能力”的意思，而may与might则不具此意。例如：
1）According to the weather forecast, it may rain tomorrow.
2) Any man with a little n can e that he is wrong.
（2）May I / we …？这一类疑问句的肯定回答为Yes, plea.或Certainly；否定回答为Plea don’t.或No, you mustn’t. 例如：
“May we leave now?” “No, you mustn’t. You haven’t finished your home work yet.”
4. can 和 be able to
can 与 be able to 都可以表示能力，但两者在用法上有点差异：can (could)表示主观能力，不表示意愿，它的将来时用will be able to; be able to表示主观意愿，强调要克服困难去做某事。例如：
1）My grandma is over venty, but she can still read without glass.
2）He is able to give up his bad habits.
5. must 和 have to
must 和 have to 都可以表示“必须”，但有几点区别：
