MODAL VERBS LY THUYET

MODAL VERBS 1: MUST/CAN/SHOULD, OUGHT TO
I. MUST
MEANING 1
We use MUST when we want to say that it is necessary or very important that something
happens in the present or future.
E.x.
- I must work hard on my English! (note: this expresses an obligation that you place on yourself.)
- Students must pass an entrance examination to study at this school.
- You must take some medicine for that cough. strong recommendation
- Plants must have light and water to grow.
Note:
Negative form is: Don’t have to do
E. x. You don’t have to clean the floor.
Past form: Had to do/didn’t have to do
E. x. I had to clean the house yesterday.
MEANING 2
We use MUST to make an assumption or to reach a logical conclusion about something that is
very likely to be true.
E. x.
- You must be so tired after running that marathon! (note: this means ‘I assume that you
are so tired.’)
- It’s not very warm and you are not wearing a coat. You must be cold. (= I'm sure you are cold.)
- Mrs. Woods must know London very well. She has lived there all her life.(= I’m sure she knows
London very well.)
- You’ve been travelling all day. You must be tired.
- Carol does the same thing every day. She must get bored in her job.
- Jack must be home. I heard a noise coming from his room.
Note:
Negative: Can’t do
E. x.
- You've just get lunch. You can’t be hungry.

- They haven’t lived here very long. They can’t know many people.
Past form: Must have done/Can’t have done
E. x.
- My bicycle has disappeared – someone must have stolen it. (note: this means ‘I assume that
someone has stolen it.’)
- You must have been so cold when you were locked out of your house in the snow! (note: this
means ‘I assume that you were so cold.’)
- Those jackets you bought are very nice. They must have been expensive.
- I’ve lost one of my gloves. I must have dropped it somewhere.
- He has rung the doorbell three times but nobody has answered it. They must have gone out.
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- The ground was wet this morning. It must have rained last night.
- He didn’t eat any lunch – he can’t have been hungry. (note: this means ‘ I assume that he was not
hungry.’)
- Jane walk past me without speaking. She can’t have seen me.
- You can’t have been at the cinema yesterday. The cinema was closed all day yesterday.
CAN’T HAVE DONE = COULDN’T HAVE DONE
MEANING 3
We use MUST to give emphasis to an opinion.
E.x.
- I must admit, it was a frightening experience. (note: we use ' I must admit' before a surprising or
negative comment.)
- I must say, this food is delicious! (note: in this sentence, we would not say ‘I must admit, this food
is delicious!’ because it would mean that we did not expect the food to be delicious. This would
sound a little rude!)
- I must admit, I didn’t like him much when I first met him.
- I must say, you look really well! Have you been on holiday?
MEANING 4

We use MUST to emphasise that we think it is a good idea for someone to do something
pleasant. It is a way of giving a recommendation.
Examples:
- You must come and visit us while you are in London!
- We must go and see that film.
- I have heard it is excellent!
MUST can also be used as a NOUN
Meaning: We say something is a MUST if it is really necessary to have it.
E. x. If you are visiting London, a good map is a must.
.
MUSTN’T
The negative is Mustn't which refers to prohibition (negative obligation)
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You mustn't use your smart phone while you are driving.
You mustn't get on the subway if you haven't paid for the ride.
You must not open the gift until it is your birthday.
We must not tell anyone.
You must keep it a secret. You mustn’t tell anybody else.
This food must not be eaten. It has gone bad.
Pupils must not run in the corridors. (note: here, ‘must’ expresses a school rule.)
Jenny, you must not play in the street!

II. CAN:
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"Can" is one of the most commonly used modal verbs in English. It can be used to express ability
or opportunity, to request or offer permission, and to show possibility or impossibility.
Examples:
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I can ride a horse. ability
We can stay with my brother when we are in Paris. opportunity
She cannot stay out after 10 PM. permission
Can you hand me the stapler? request
Any child can grow up to be president. Possibility
We can see the lake from our bedroom window.
I can come and see you tomorrow.

- Be able to do: can be used in place of “can” but ‘can” is more common.
E.x. - We are able to see the lake from our bedroom window.
- I am able to come and see you tomorrow.b
However, “can” has only two forms, present Can and past Could .So we have to use “be able to do”
when necessary.
E.x. - I can’t sleep.
- But I haven’t been able to sleep recently.

III. So sánh should và ought to
1. Dạng thức
1.1 Dạng khẳng định:
S+ should + V
S+ ought to + V
Ví dụ:
You should see a doctor if your cough gets worse. (Ông nên đi khám bác sĩ nếu bị ho
nặng hơn.)
You ought to see a doctor if your cough gets worse. (Ông nên đi khám bác sĩ nếu bị ho nặng
hơn.)
1.2 Dạng phủ định:
S+ should not (shouldn't) + V
S+ ought not to (oughtn't to) + V
Ví dụ:
Mrs. Smith shouldn't keep complaining. (Bà Smith không nên tiếp tục phàn nàn nữa.)
Mrs. Smith oughtn't to keep complaining. (Bà Smith không nên tiếp tục phàn nàn nữa.)
Lưu ý: Dạng thức phủ định của “ought to” không được sử dụng phổ biến bằng dạng thức phủ định
của “should”
1.3 Dạng nghi vấn:
Should +S+V
Ought + S + to + V
Ví dụ:
Should we care about the environment? (Chúng ta có nên quan tâm tới mơi trường
khơng?)
Ought we to care about the environment? (Chúng ta có nên quan tâm tới môi trường không?)
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Lưu ý: Dạng thức nghi vấn của “ought to” không được sử dụng phổ biến bằng dạng thức nghi vấn
của “should”

2. Cách sử dụng
2.1 Điểm giống: Cả “should” và “ought to” được sử dụng khi hỏi và đưa ra lời khuyên hoặc gợi ý.
Ví dụ:
You should learn English every day. (Bạn nên học tiếng Anh hàng ngày.)
You ought to learn English every day. (Bạn nên học tiếng Anh hàng ngày.)
2.2 Điểm khác: Giữa “should” và “ought to” có sự khác biệt nhỏ trong sắc thái của lời khuyên.
Should
Ought to
Dùng cho lời khuyến mang tính chủ quan, thể Dùng với những lời khuyên mang yếu tố khách
hiện quan điểm cá nhân của người nói
quan, tức là có sự tác động của ngoại cảnh như
luật lệ, bổn phận hay quy tắc
Ví dụ:
Linda should go to bed early.
Ví dụ: Emily ought to finish the report by 10
(Linda nên đi ngủ sớm.)
a.m. (Emily nên hoàn thành bản báo cáo trước
10 giờ sáng.)
MODAL VERBS (PERIOD 2)
PERFECT MODAL
I. Could, May, Might + Have + P2: Có lẽ đã......
1. Diễn đạt một điều gì đó có thể đã xảy ra hoặc có thể đúng ở quá khứ song người nói khơng
dám chắc.
E.x
- She didn’t hear the telephone ring. She might have been asleep at that time. (Tôi đã khơng nghe
thấy chương điện thoại, lúc đó có lẽ tôi đã ngủ.)
- John might have gone to the movies yesterday. (John có lẽ đã đi xem phim ngày hơm qua.)
- “I can’t find my bag anywhere”. – “You might have left it in the shop.”
Note: Thể phủ định là: Might not/May not have done
E.x.

- I was surprised that Mary wasn’t at the meeting.
She might not have known about it.
- I wonder why Mary was in such a bad mood yesterday.
She may not have felt well.
2. Diễn đạt điều gì đó có thể xảy ra nhưng đã khơng xảy ra: Lẽ ra đã có thể
E.x.
- Why did you leave him come home alone? He might/could have got lost. (Sao anh lại để nó đi về
nhà một mình? Nó có thể đã bị lạc) → Sự thật là nó khơng bị lạc
II. Should + Have + P2 = lẽ ra phải, lẽ ra nên
1. Chỉ một việc lẽ ra đã phải xảy ra trong q khứ nhưng vì lí do nào đó lại khơng xảy ra
E.x.

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- Maria should have called John last night. (Lẽ ra tối qua Maria nên gọi cho John.) → Nhưng cô ấy
đã không gọi.
- That was a great party. You should have come.
- I wonder why they are so late. They should have been here an hour ago.
- You went to bed very late last night. You should have gone to bed earlier.
Phủ định là: Shouldn’t have done
E.x.
- I’m very fat. I shouldn’t have eaten so many sweets.
- She is feeling sick. She shouldn’t have walked in the rain.
Chúng ta cũng có thể dùng cụm từ Was/Were supposed to + V để thay cho should + have + P2
E.x.
- John was supposed to go to the post office this morning.
- The policeman was supposed to make a report about the burglary.
2. Should have done đươc dung để nói về những sự việc đã khơng hoặc có thể đã khơng xảy ra
trong quá khứ. Chẳng hạn:

- I should have finished this work by now. - Đáng lẽ bây giờ tôi đã phải hồn thành cơng việc này
rời (mà đến giờ tơi vẫn chưa làm xong).
- I should have studied harder for my exams - Đáng lẽ tôi phải học chăm chỉ hơn khi chuân bị cho
các kỳ thi của tôi.
Trong cả hai câu trên, người nói có thể bày tỏ thái độ ân hận, lấy làm tiếc là đã không làm một việc
gì đó.
Chúng ta cũng có thể dùng should have done để diễn tả những nghĩa vụ đã khơng được hồn thành,
thực thi.
E.x.
- He should have helped his mother carry the shopping.
III. Might Have Been + V-ing: Có lẽ lúc ấy đang.
Ví dụ:
- I didn't hear the telephone ring, I might have been sleeping at that time.
- Tôi không nghe tiếng chng điện thoại, có lẽ lúc ấy tơi đang ngủ.
IV. Must have been V-ing: Hẳn lúc ấy đang.
Ví dụ:
- I didn't hear you knock, I must have been gardening behind the house.
(Tôi không nghe thấy tiếng gõ, hẳn là lúc ấy tơi đang làm vườn phía sau nhà.)
V. Could Have Done: Chúng ta thường sử dụng "could have (done)" cho những việc có thể xảy ra
nhưng đã khơng xảy ra.
- I’m so tired. I could sleep for a week. (now)
Tôi mệt q. Tơi có thể ngủ cả tuần liền. (hiện tại)
- I was so tired. I could have slept for a week. (past)
Tơi đã mệt q. Tơi đã có thể ngủ cả tuần liền. (quá khứ)
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- Why did you stay at a hotel when you went to New York? You could have stayed with Barbara. (=
you had the opportunity to stay with her but you didn’t)
Tại sao bạn lại ở khách sạn khi bạn đến New York? Bạn có thể ở với Barbara cơ mà. (=bạn đã có cơ

hội ở với cơ ấy nhưng bạn không thực hiện)
- Jack fell off a ladder yesterday but he’s all right. He’s lucky - he could have hurt himself badly. (but
he didn’t hurt himself)
Ngày hôm qua Jack đã ngã xuống từ một cái thang nhưng anh ấy không hề gì. Anh ấy thật may mắn
- anh ấy lẽ ra đã bị thương rất nặng. (nhưng anh ấy đã khơng bị thương gì hết)
- The situation was bad but it could have been worse.
Tình hình là xấu nhưng nó đã có thể tời tệ hơn nhiều.
- Why didn’t Liz apply for the job? She could have got it.
Tại sao Liz đã không nộp đơn xin việc nhỉ? Cô ấy đã có thể được nhận.
- I could have lent you the money. Why didn’t you ask me?
IV. Needn’t have done: Đã làm việc gì trong q khứ nhưng điều đó hóa ra khơng cần thiết
- We needn't have hurried. We got there far too early.
- You needn't have worried. You can do it.

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