PHÂN BIỆT MODAL VERBS: MUST VS. HAVE TO, SHOULD VS. OUGHT TO

UNIT 1: THE GENERATION GAP
VOCABULARY
WORD
Afford
/əˈfɔːd/
Attitude
/ˈætɪtjuːd/
Burden
/ˈbɜːdn/
Casual
/ˈkæʒuəl/
Comfortable
/ˈkʌmftəbl/
Compare
/kəmˈpeə(r)/
Conflict
/ˈkɒnflɪkt/
Control
/kənˈtrəʊl/
Dye
/daɪ/
Elegant
/ˈelɪɡənt/
Flashy
/ˈflæʃi/
Forbid
/fəˈbɪd/
Force
/fɔːs/
Interact
/ˌɪntəˈrækt/

Judge
/dʒʌdʒ/
Mature
/məˈtʃʊə(r)/
Obey
/əˈbeɪ/
Norm
/nɔːm/
Rude
/ruːd/

PART
MEANING
OF
SPEECH
(v)
(n)
(n)
(adj)
(adj)
(v)
(n)
(v)
(v)
(adj)
(adj)
(v)
(v)
(v)
(v)

(adj)
(v)
(n)
(adj)

EXAMPLE


MODAL VERBS: MUST VS. HAVE TO, SHOULD VS. OUGHT TO
I. GIỚI THIỆU CHUNG VỀ ĐỘNG TỪ KHUYẾT THIẾU
1. Cách sử dụng
Động từ khuyết thiếu được dùng để nêu lên khả năng thực hiện hành động, sự bắt buộc, khả
năng xảy ra của sự việc, v.v.
2. Hình thức
- Theo sau chủ ngữ và đứng trước động từ ngun thể khơng có "to"
- Không chia theo chủ ngữ (trừ trường hợp "have to")
- Thêm "not" phía sau khi ở dạng phủ định (trừ trường hợp "have to")
Eg: I must go. (Tôi phải đi rồi.)
He should not disturb her now. (Anh ta không nên làm phiền cô ấy lúc này.)
II. SO SÁNH MUST VÀ HAVE TO
1. Dạng khẳng định
Must: Diễn tả sự cần thiết hay bắt buộc mang tính chủ quan (do người nói quyết định)
S + must + V
Eg: I must finish the exercises. (Tơi phải hồn thành bài tập.)
(Tình huống: I'm going to have a party. (Tơi có ý định đi dự tiệc.))
Have to: Diễn tả ý bắt buộc mang tính khách quan (do luật lệ, quy tắc hay người khác quyết
định)
S + have to/ has to/ had to/ ... + V
I have to finish the exercises. (Tơi phải hồn thành bài tập.)
(Tình huống: Tomorrow is the deadline. (Ngày mai là hạn cuối.))

2. Dạng phủ định
Must not: Diễn tả ý cấm đoán
S + must not (mustn't) + V
Eg: you must not eat that. (Bạn khơng được phép ăn cái đó.)
(Tình huống: It's already stale. (Nó đã bị thiu rồi.))


Not have to: Diễn tả ý không cần phải làm gì
S + do not (don't)/ does not (doesn't)/ did not (didn't)/ will not (won't)/ ... + have to + V
Eg: You do not have to eat that. (Bạn không cần phải ăn thứ đó.)
(Tình huống: I can see you dislike that. (Mình có thể thấy rằng bạn khơng thích nó.))
III. SO SÁNH “SHOULD” VÀ “OUGHT TO”
1. Dạng thức
1.1 Dạng khẳng định:
S + should + V
S + ought to + V
Eg: 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
Eg: 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

Eg: Should we care about the environment? (Chúng ta có nên quan tâm tới môi trường
không?)
Ought we to care about the environment? (Chúng ta có nên quan tâm tới mơi trường khơng?)
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
Eg:
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 khuyên mang tính chủ quan, Dùng với những lời khuyên mang yếu tố
thể hiện quan điểm cá nhân của người nói khách quan, tức là có sự tác động của ngoại
cảnh như luật lệ, bổn phận hay quy tắc
Eg:
Eg:
Linda should go to bed early.
Emily ought to finish the report by 10 a.m.
(Linda nên đi ngủ sớm.)
(Emily nên hoàn thành bản báo cáo trước 10
giờ sáng.)
IV. BÀI TẬP
I. Match the advice with the suitable situation.
I don't feel well.
All fruits on the tree are ripe.

I have a toothache.
I have a test tomorrow.
I can't speak English well.
I’m hot

You ought to pick them up immediately
You ought to review all lesson tonight
You should go to a doctor
You ought to go to the dentist
You should practice English everyday
You should talk to her about your
feelings
I feel tired
You should take a rest
John is always late for school
He should manage his time better
I want to lose weight
You should do the exercise regularly
My mother reads my diary
You should turn on the fan
II. Find ONE mistake in each sentence and fill in the blank with the correct word.
1.You must eats more fruit and vegetables every day.
=>________________________________________________________________________
2.I have to tidied my room before my mother comes back home. She can't stand a messy
house.
=>________________________________________________________________________
3.She should go out late at night because of danger.
=>________________________________________________________________________
4.She have to speak English well because her current job needs it.
=>________________________________________________________________________

5.He musts save up his money so as to buy a new house next year.


=>________________________________________________________________________
6.He oughtn't to find another solution to this problem if he doesn't want to get fired.
=>________________________________________________________________________
7.They can arrive at the airport at 5 so as not to miss their flight at 6.
=>________________________________________________________________________
8.I have to submit my essay last night. My teacher set the deadline on that day.
=>________________________________________________________________________
9.You ought to stay up at night, which is not good for your health.
=>________________________________________________________________________
10.We haven't to buy souvenirs for Sally. She doesn't like them.
=>________________________________________________________________________
III. Complete the sentences using the given words.
Mustn’t, don’t have to, should, ought
1.You ___________________ type your essay but if you want, you can do it.
2.I __________________ go home too late. My parents are very strict.
3.She is an expert adviser; thus, I think you ______________________ to ask her for some
advice.
4.You ____________________ ask your teacher if you don't understand the lesson.
Should, have to, ought not, must
1.I_____________________ finish homework before coming to class. My teacher is rather
strict.
2.We _____________________ show respect to our parents.
3.I think you ____________________ stay up late because it is not good for your health.
4.If you want to help your friend, you ______________________ to do her homework.
Instead, you should show her how to do it by herself.
IV. Click on one of the two bold words which best completes the sentences.
1.It's cold. You should/shouldn't turn on the fan.

2.You ought not to/ought to do homework before you go out with your friends.
3.You should/shouldn't eat plenty of fruit or vegetables every day in order to keep healthy.
4.You must/mustn't eat in the class.
5.You ought to/ought not to drink a lot of water every day.


6.I must/have to submit my homework before 12 o'clock because the deadline is 12 o'clock.
7.I must/have to stay at home to take care of my children.
8.My friend says: "You don't have to/mustn't drink champagne. You can have a coke or
fruit juice instead.
9.You don't have to/mustn't drink if you're going to drive afterwards.
10.You don't have to/mustn't pick up Tom at the airport because Judy will pick him up.
V. Fill in the gaps with “must” and “have to”. Use the negative form if necessary.
1.Tomorrow is Mai's birthday. I _______________ buy a present for her.
2.We might _________________ leave earlier than we expected.
3.If you feel better, you _________________ take medicine any more.
4.I ________________ leave home at 6:00 because I have an appointment at 7:00.
5.You __________________ eat a lot before doing the exercise. If you do, you might get
into some trouble with your stomach.
6.We couldn't find a better present so we _______________ choose this one.
7.If you are a member of the club, you ____________pay to use these facilities because they
are included in the membership fee.
8.I had the flu, so I ________________ stay in the bed for two days.
9.If you are under 18 years old, you ________________ ride a motorbike.
10.All students ___________________wear uniforms on Mondays because it's the rule.
VI. Rewrite each sentence using the word(s) in the brackets, without changing its
meaning.
1.If I were you, I would spend more time talking with my children. (should)
=> ________________________________________________________________________
2.John doesn't get permission to use that computer. (mustn't)

=> ________________________________________________________________________
3.It is necessary that people who work here leave by 6 p.m. (must)
=> ________________________________________________________________________
4.Every staff isn't allowed to smoke or eat in the office. (mustn't)
=> ________________________________________________________________________
5.Customers are advised to check their luggage before leaving the airport. (ought to)
=> ________________________________________________________________________
6.It is forbidden for students to cheat in the exam. (mustn't)


=> ________________________________________________________________________
7.Ms. Ly is in charge of cleaning the floor every day. (has to)
=> ________________________________________________________________________
8.You are not allowed to take photographs in the museum. (mustn't)
=> ________________________________________________________________________
9.It would be a good idea for you to share the housework with your mother. (ought to)
=> ________________________________________________________________________
10.It is not necessary for Jack to call Ben today. (doesn't have to)
=> ________________________________________________________________________