1、can/could
- can/could表示能力,用
be able to
代替,can/could现在/过去的能力客观可能性(can
的可能性大),表示请求和允许。
-
例句
- He can/could/is able to swim.
- He can/could come tomorrow.
- can/could(
比较委婉
) I stay here?
2、may/might
- may//might表示可能性,(
may
的可能性大)请求,允许(might
更委婉)。
- 口语中常用的回答:
- Yes,please.
- No,you can‘t/mustn’t(禁止,不准).
-
例句:
- He may/might come here by bus.
- May/might I join you?
回答:
- Yes,please.
- No,you can’t.
- No,you mustn’t
3、must/have to
- must/have to 表示必须、必要(must表示主观多一些,而have to 则表示客观多一些)。
have to有时态和数量的变化
。
- must和have to二者的否定意义不大相同。
如:
- You mustn’t go. //你不准去
- You don’t have to go. //你不必去
-
例句:
- You must get up early.
- It’s going to rain,I have to go home now.
4、should/ought to
- should/ought表示劝告、建议命令,should强调主观看法,而ought to强调客观要求。在疑问句中,通常用should代替ought to.
-
例句:
- You should/ ought to do the job right now.
- Should they stay here now.
5、need
- need(需要):
- 情态动词;
- 实意动词,有第三人称单数和时态的变化后面课加带to的不定式。
5.1、情态动词
-
例句:
- He need come here early.
- He needn’t come here early.
- Need he come here early?
回答: Yes,he need./No,he needn’t.
5.2、实意动词
-
例句:
- He needs to come here early.
- He doesn’t needs to come here early.
- Does he need to come here early?
回答:Yes,he does. No,he doesn’t。
5.3、don’t have to
- 回答must和have to的提问句时,否定式使用
needn't,don't have to
等回答方式。
-
例句:
- Must I come here early tomorrow?
回答:No,you needn’t./No,you don’t have to.
6、had better
- had better表示“最好做某事”,had虽然是过去式,但不表示过去,better后面接动词原形。
- 否定形式为:had better not+动词原形。
-
例句:
- He had better eat more.
- You’d better finish it right now.
- He had better not eat more.
7、would rather
- would rather 表示“宁愿、宁可、最好、还是···为好”,语感上比“had better”要轻。
- 否定形式为:would rather not+动词原形。
-
例句:
- You would rather deal with it now.
- You would rather not deal with it now.
8、user to/would
- used to/would表示过去习惯性动作,可翻译为“过去常常···”。
- used to可指过去的状态或情况,would则不能。
The novel used to be popular.
- would表示反复发生的动作。如果某一动作没有反复性,就不能用would,只能用used to。
He would practise English every week.
I used to live in Beijing.
- used to表示过去经常性或习惯性的动作或状态现在已经结束,would则表示有可能再发生。
-
例句:
- People used to believe that the earthe was flat.
- He would go to the park as soon as he was free.
9、情态动词否定和疑问
9.1、情态动词的否定
- 情态动词+not+动词原形
-
例句:
- He can’t sing an English song.
- He may not know her.
- He mustn’t go there.
- He doesn’t have to go there.
9.2、情态动词的提问
- 情态动词+主语+动词原形
-
例句:
- can he sing an English song? 回答:Yes,he can./No,he can’t.
- Must he go there? 回答:Yes,he must./No,he needn’t.
- Does he have to go there? 回答:Yes,he does./No,he doesn’t.
10、情态动词+have+p.p
- 情态动词+have+p.p
- 表示过去事实。
- 推测的含义。
- 助动词should例外
-
例句:
- He must have arrived.
- He can/could have arrived.
- He may/might have arrived.
- should+have+p.p:本应该…;needn’t have+p.p:本不需要···;
-
例句:
- He sould have arrived.
- They should have finished the work.
- You needn’t have done so.
- must have p.p:准是已经···;can’t have p.p:不可能已经···
-
例句:
- He must have arrived.
- He can’g have arrived.
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