2018年专四英语情态动词语法考点
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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)某些情态动词的特殊用法
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:
Since the ditch is full of water, it must have rained last night.
2. could have v-ed 表示推测过去某动作“很可能”发生了
3. may / might have v-ed 表示推测过去某事“也许”发生了 比 might 表示的可能性在说话人看来稍大些。
t 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…”表示应完成而未完成的动作用于完成时中的否定句,表示不应完成但已做的动作
n’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.
注意:did not need to do 动作并没发生
例:I didn’t need to get up early,so I got up until 9 a.m.
*特殊用法
(1) can‘t表示“不可能”, may not 表示“不可以”, mustn’t(must not) 表示“不许可 禁止”,needn't (need not) 表示“不必”,dare not +动词原形 表示“不敢”
(2) must表推测 的否定现在式用can’t ,过去式用couldn’t
(3)May I / we …?这一类疑问句的肯定回答为Yes, please.或Certainly;否定回答为Please 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) need I / we …?这一类疑问句的肯定回答为Yes, we must; 否定回答为needn’t
(5)在回答must引起的问题时,如果是否定的答复,不能用mustn’t,而要用needn’t或don’t have to
(6)May/might as well may……but….(表转折)
(7) I wish to go home with you, may I?
(8) Do help yourself to have fruit, won’t you/ will you? (表示一种委婉的请求)
*情态动词短语的使用
would like to do…
would rather do…
would rather + 从句
would prefer to do...
had better do...
*情态动词: will(愿意), shall(将), must(必须), can, may, would, should(应该), might, could, ought to, used to(过去常常), need(需要), dare(竟敢),have to(不得不)
*dare, need 也可作一般(行为)动词
*情态动词一般用法的否定:
mustn’t 不准, 禁止,不要 can’t(couldn’t) 不会;不能;
may (might) not 不可以;
needn’t 没必要 ( = don’t have to )
used not/usedn’t to或didn’t use to… 过去不…
dare not 不敢
*情态动词推测用法
Must 一定,肯定 can’t (couldn’t) 不可能
Can/ could 可能 Can’t (couldn’t) 不可能
may/ might “可能,也许” May (might) not 也许不,可能不
*推断用法
should/ought to“按理应当,应该是; shouldn’t 不应该 ( = ought not to )
*情态动词+have +done结构表示对过去动作的`推测
1. must have done:对过去的肯定推测,译作“一定做了…”,只能用于肯定句中。
其否定形式为can’t/couldn’t have done?
It must have rained last night, for the road was quite muddy
2. can/ could have done:对过去的可能性推测,译作“可能做了…”。只能用疑问句中
Can/Could he have said it? 他可能说过那种话吗?
3. may / might have v-ed:对过去的可能性推测,译作“也许能,有可能。
It’s too late. I think he may have gone to bed.
*情态动词+have+过去分词结构表示轻微的责备和后悔
肯定:过去应该做而没有做;
否定:过去不该(不必)做而做了。
⑴ might/could+have+过去分词:“本来可以,早就应该”
(只用于肯定句,且不能用may, can)
You could have told me you were going to be late!.你应当早告诉我你会晚到的!
⑵ should(ought to)+have+过去分词:“本应”(没做)
should not(ought not to)+have+过去分词:“本不该”(做了)
You should not have handed in your composition yesterday morning.你本不应把作文交了。
You should have been here earlier.你应该早点来才对。
3. needn't+have+过去分词:“本不必,本不须”(need只用于否定句)(做了)
You needn't have woken her up. It's only six.你其实不必叫醒她。现在才六点。
注意:did not need to do 动作并没发生(没做)
例:I didn’t need to get up early, so I got up until 9 a.m.
*八大注意点
1.在以could, might 表示征询对方意见或表示请求时,回答应相应使用can, may
— Might I watch TV after supper? — Yes, you ________.
A. may B. must C. might D. can
2. May I / we …?这一类疑问句的肯定回答为Yes, please.或Certainly;否定回答为Please 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.”
3. need I / we …?这一类疑问句的肯定回答为Yes, we must; 否定回答为needn’t
4. 在回答must引起的问题时,肯定must; 如果是否定的答复,不能用mustn’t,而要用needn’t或don’t have to
5. I wish to go home with you, may I?
6. Do help yourself to have fruit, won’t you/ will you? (表示一种委婉的请求)
l 用于第三人称,表示许可,允许
8. let’s do this job, shall we? Let us do this job, will you?
9. should 也表示惊讶的语气,
例如:I was shocked that she should have said such a thing to you.(她竟然对你说那样的话,…)
*四大特殊结构
might as well + 动词原形”意为“最好,满可以,倒不如”,相当于had better
You may as well do it at once.
well + 动词原形”是一种常见的结构,意为“(完全)能,很可能”
He may well be proud of his son.
他大可为儿子高兴。
3. cannot … too / enough 表示 “无论怎么……也不算过分”、“越……越好”
You cannot be too careful.
4. had better 最好
You had better not wake me up when you come in.
*两大类区别:
一、表示能力: can, be able to
be able to 能用于各种时态。
can / could 只能表示现在或过去的能力
*was / were able to : “设法做成某事”
相当于 managed to do sth succeeded in doing sth.
二、used to 和would 的区别
used to过去常常(但现在已无此习惯,would无此含义)
He used to drink beer, now he drinks wine.他过去喝啤酒,现在喝白酒。
would只能用来谈动作;used to用来谈动作或状态(可与be, live, like, stay等状态动词连用):
He would get up early when he lived in the country.他住在乡下时总是早起。
We used to live in a small town.(不能用would)
Be used to doing sth: 习惯于做某事