had better, should, ought to学习四要素
had better, should, ought to 均为提建议型情态动词，常用来劝告别人去做某事，没有人称和数的变化，学习时应注意下列几点：
一 . 掌握基本用法
had better, should, ought to 含义及语气有所不同，请看下表：
二 . 掌握创新用法
should 可表竟然，强调惊讶的情绪。
I can't imagine this problem should be so easy.
我想像不出这个问题竟然这么容易。
had better 也可改为 had best ，其意义和用法不变。
I'm busy now, so you had best go there alone.
我现在很忙，所以你最好单独去那儿。
三 . 掌握句型变换方法
had better, should, ought to 均属于助动词，其疑问句、否定句及反意疑问句的构成均在自身形式上做变化。
1. 变成否定句方法
had better do 否定式为 had better not do, should do 否定式为 should not do 或shouldn't do, ought to do 否定式为 ought not to do 或 oughtn't to do 。
2. 变成一般疑问句方法
had better, should, ought to 构成一般疑问句时应分别将 had, should, ought 提到句首，其肯定与否定回答为 had / hadn't, should / shouldn't, ought / oughtn't 。
3. 变成反意疑问句方法
had better, should, ought to 构成反意疑问句时通常使用 had / hadn't, should / shouldn't, ought / oughtn't 形式。
She had better water the flowers as soon as possible, hadn't she?
她最好尽快给花浇水，不是吗？
All of us should take an active part in this activity, shouldn't we?
wolfenstein
我们都应该积极参加这次活动，不是吗？
They oughtn't to go fishing in this river, ought / should they?
他们不该在这条河里钓鱼，是吗？
四 . 掌握完成式用法
should 与 ought to 完成式意义和用法相同，可以通用。 should / ought to have done sth. 本来应该做某事但实际未做，表达一种遗憾的感情色彩。 shouldn't / oughtn't to have done sth. 本来不应该做某事但实际已做了，也表达一种遗憾的感情色彩。 had better 没有完成式。
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The meeting has already begun. You should have come here half an hour ago.
会议已经开始了，你本来应该半小时之前就到这儿。
She is very sad now. You oughtn't to have told her the news.
她现在很难过，你本不该把这消息告诉她。
［巩固练习］
I. 从 A 、 B 、 C 、 D 中选出可以填入空白处的最佳答案。
1. This dictionary belongs to Rita. You ____________ it home without letting her know.
A. had better not to take
B. shouldn't have taken
C. oughtn't take
D. shouldn't be taking
2. Our money is very limited, so you ___________ so much money on so dear a skirt.
A. shouldn't have spent
B. shouldn't be spending
打电话英文C. needn't have spent
D. oughtn't spend
3. You __________ to your father like this, after all he is your father.
A. needn't have spoken
B. mustn't have spoken
C. oughtn't to have spoken
D. ought to not have spoken
siliuji4. I really can't understand such a beautiful girl like her _________ be so rude.
A. must
B. would
C. should
D. might
5. Look, the books on the desk are all wet. You __________ all the windows to keep the rain out.
A. must have shut
B. should have shut
C. ought have shut
D. can have shut早教英语儿歌
6. The little girl had better not stay up too late, ___________ she?
A. does
B. will
C. had
ycuD. has
7. This is a very important project, so you _______ plan it very carefully.
A. ought to
vigaaB. will
C. dare
D. need
网络的利弊8. You had better ________ football near the street, it's very dangerous.
A. not to play
B. don't play
C. not play
D. to not play
II. 在下列各句的空白处填上适当的情态动词，每空一词。
1. — Excu me, may I sit here?
— I'm afraid you ________ ________ not, becau someone has taken it.
2. Tom, you __________ have left home without telling your parents yesterday afternoon.
3. You _________ __________ have bought that book. It is so good.
4. I think you should be careful in all your work, ____________ you?
5. Your sister ought to put her heart and soul into her study, _____________ she?
答案：
I. 1. B 2. A 3. C 4. C
approach是什么意思5. B
collapd
6. C
7. A
8. C
II. 1. had better 2. shouldn't
3. ought to
4. shouldn't
5. oughtn't
