- Have to thƣờng đƣợc dùng diễn tả sự bắt buộc nói chung để phải làm một việc gì đó, nó bắt nguồn từ ngoại cảnh, nhƣ các luật lệ, nguyên tắc.. - Must diễn tả sự bắt buộc phải làm bắt ngu[r]
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CHUYÊN ĐỀ 5: ĐỘNG TỪ KHUYẾT THIẾU (MODAL VERBS)
A Obligation ( băt buộc)
Must, have to, should
1 Obligation/ necessity: Have to/ must (+ infinitive)
- Have to thường được dùng diễn tả sự bắt buộc nói chung để phải làm một việc gì đó,
nó bắt nguồn từ ngoại cảnh, như các luật lệ, nguyên tắc
- Must diễn tả sự bắt buộc phải làm bắt nguồn từ chủ thể của hành động
So sánh:
I have to wear a shirt and tie at work (It‘s the rule in this company)
I must buy a new shirt – this one is too old now ( It‘s my own decision)
Have to là động từ bình thường và sử dụng được ở tất cả các thì
Must là động từ khuyết thiếu và chỉ có 2 dạng: Must – mustn‘t
Có thể sử dụng have to hoặc must để nói về sự giới thiệu mạnh mẽ
Eg: You have to/ must see that film – it‘s fantastic
2 No obligation/ necessity: Don’t have to
You don‘t have to pay for the tickets They‘re free
You don‘t have to go to the party if you don‘t want to
3 Prohibition: Mustn’t (+ infinitive)
You mustn‘t eat that cake – it‘s for the party
You mustn‘t touch that It‘s dangerous
So sánh:
You mustn‘t drive along this street = It‘s prohibited, against the law ( Nó bị cấm)
You don‘t have to drive – we can get a train = You can drive if you want to but it‘s not necessary ( Bạn có thể lái xe nhưng nếu bạn không muốn, nó không cần thiết)
Thường chúng ta có thể sử dụng can‘t hoặc not allowed to thay vì mustn‘t
Eg: You mustn‘t park here You can‘t park here You are not allowed to park here
Advice or opinion : Should/ shouldn‘t, ought to, ought not to
Dùng Should/ shouldn‘t, ought to, ought not to khi chúng ta nghĩ rằng điều gì đúng hay sai để làm
Eg: You should take warm clothes with you to Dublin It might be cold at night
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B Deduction
Must, may, might, can‘t ( Dùng khi nói về chúng ta chắc chắc thế nào về điều gì đó, dựa vào thông tin ta có)
Khi chắc chắn điều gì đó là đúng: Dùng must
Eg: They must be out There aren‘t any lights on
She must have a lot of money She drives a Porsche
Khi bạn nghĩ điều gì có thể đúng: May/might
Eg: His phone‘s switched off He might be on the plane now
She might not like that skirt It‘s not her style
She‘s not at home She may be working
He hasn‘t written He may not have my address
Khi bạn chắc chắn điều gì là không thể/ không đúng: Dùng can‘t
He can‘t be ill I saw him at the gym
They can‘t be Italian They‘re speaking to each other in Spanish
C Ability and possibility ( can, could, be able to)
Can/could
Can chỉ dùng ở thì hiện tại, và quá khứ ( could)
Could có thể dùng ở hiện tại, thể hiện sự lịch sự khi nói
I can speak Spanish very well
She could play the violin when she was three
She can‘t come tonight She‘s ill
They couldn‘t wait because they were in a hurry
Could you open that door, please?
Be able to + infinitive
Be able to có thể dùng cho tất cả các thì
Be able to trang trọng hơn can/ could
Eg: I am able to accept your invitation
They weren‘t able to come
I‘ll be able to practice my English in London
She has been able to speak French since she was a child
I‘d like to be able to ski
I love being able to sleep at weekends
D Other modal verbs
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1 Needn’t
Người nói cho rằng người nghe không cần phải làm điều gì
_ Youneedn’t buy this
_ We needn’t hurry We still have a lot of time
2 Don’t need to
Thay cho needn’t; quá khứ dùng didn’t
_ Mark doesn’t have to finish the report today He can do it at the weekend
_ You don’t have to wash those glasses They‘re clean
_ He didn’t need to take a coat It was a lonely day
3 Had better ( Nên)
Had better sử dụng giống hệt should
Thể phủ đinh: had better not
4 Ought to ( Nên)
Ought to sử dụng giống hệt should
Thể phủ đinh: ought not to/ oughtn‘t to
E MODAL PERFECT
1 Must have + past participle
Ắt hẳn đã xảy ra trong quá khứ
- I have lost one of my gloves I must have dropped it somewhere
- My watch says only ten past six It must have stopped
2 Should(n’t) have + past participle
(Không) nên làm gì trong quá khứ
You shouldn’t have come to school so late
We didn‘t play very well We should have played better
3 Ought to have + past participle
You ought to have asked me before you took my bike
We ought to have been more carefully in our exam
4 Needn’t have + past participle
Không cần làm một việc gì trong quá khứ
You needn’t have bought her such a precious present
We needn’t have gone to the supermarket There‘s enough food at home
5 Can’t/couldn’t have + past participle
Ắt hẳn đã không xảy ra trong quá khứ
She went to London two days ago You can’t/couldn’t have seen her yesterday
Tom couldn’t have taken a bus yesterday There aren‘t any buses on Sundays
6 May/might/could have + past participle
Có thể đã xảy ra trong quá khứ
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You may/might/could have left your book in class
Someone may/might/could have taken the keys from my bag
7 May not/mightn’t have + past participle
Có thể đã (không) xảy ra trong quá khứ
I wonder why she didn‘t say hello
She may not/ mightn’t have seen you
(Có lẽ cô ấy đã không nhìn thấy bạn, hoặc đã thấy.)
8 Would rather have + past participle
Ƣớc muốn đã không xảy ra trong quá khứ
The film at the cinema was boring I would rather have stayed home to watch TV
He studied French at school only because his parents wanted him to He would rather have studied English