In Book 2 Unit 15, we learnt to use modal verbs to talk about ability, to ask for and give permission, and to make requests. We can also use modal verbs to give advice or talk about necessity and possibility.
Usage
Giving advice and talking about necessity
We can use should / ought to / have to / must + the base form of a verb to give advice and talk about necessity. Should and ought to are less strong and less formal than have to and must.
less strong / less formalshould ought to have to muststronger / more formal
Should and ought to
We use should / should not (shouldn’t) and ought to / ought not to (oughtn’t to) to say whether something is a good idea. Should and ought to are similar in meaning, but should is less formal and more common, especially in negative forms and questions.
You should / ought to take a walk after each meal.
They should not (shouldn’t) / ought not to (oughtn’t to) park their car there.
Have to and must
We use have to and must when we think that it is important or necessary to do something. Have to is less strong and more common, especially in questions. It can be used in the simple past, simple present and
4 Modal verbs
Summer is a lovely season, when we get to enjoy the sunshine and beaches.
While having the most fun in the year, here are a few tips we ought to remember.
First, we must drink plenty of water so that there is enough water in our body. Otherwise, we may feel dizzy or even faint. We should not arrange outdoor activities between 10 am and 4 pm when the sun is the strongest. Secondly, we have to wear sunscreen whenever we go out. It may help us avoid getting brown spots on our skin. It might prevent skin cancer too.
It could also slow down the development of wrinkles. We should reapply sunscreen from time to time. Thirdly, the sea may get rough in summer. We should practise swimming in a swimming pool before heading to the sea. We should not swim at beaches without a lifeguard. If we follow the above tips, our summer will be safe and enjoyable.
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Grandma had to cook for her family when she was a child. (past) This is such a wonderful book. You have to read it. (present)
Sam will have to help his mum with the housework this weekend. (future) We can use must to talk about the present and the future, but not the past.
You must visit the doctor if you do not feel well. (present)
Ann is going to give a speech tomorrow so she must go to bed early tonight. (future) The negative forms do not have to (don’t have to) and must not (mustn’t) have very different meanings.
We use do not have to when we can do something but it is not necessary. We use must not to say it is very important or necessary not to do something.
I do not have to (don’t have to) buy this book.
I can borrow it from the library.
You must not (mustn’t) cross the road when the traffic light is red.
Yes/No-questions
We form yes/no-questions and short answers with should, ought to, have to and must like this:
Should I/you/we/they/he/she/it do it?
Yes, I/you/we/they/he/she/it should. No, I/you/we/they/he/she/it should not / shouldn’t.
Ought I/you/we/they/he/she/it to do it?
Yes, I/you/we/they/he/she/it ought to. No, I/you/we/they/he/she/it ought not to / oughtn’t to.
We usually use Should…? in spoken English as the question form of ought to is very formal.
NOTE NOTE
Do I/you/we/they
have to do it?
Does he/she/it
Yes, I/you/we/they do.
No, I/you/we/they do not / don’t.
he/she/it does. he/she/it does not / doesn’t.
Must I/you/we/they/he/she/it do it?
Yes, I/you/we/they/he/she/it must. No, I/you/we/they/he/she/it must not / mustn’t.
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Talking about possibility
When talking about present and future possibility, we can use may / might / could + the base form of a verb to mean ‘perhaps’.
more possiblemay might couldless possible
We use may or might when the possibility of something is quite high.
May and might are similar in meaning, but may expresses a slightly higher degree of probability.
The sky is so dark. It may rain soon.
I don’t have anything to do tomorrow. I might go to the cinema.
We can also use could when something is possible.
James hasn’t arrived yet. The traffic could be bad.
We use may not and might not to say it is possible that something will not happen.
The sky is clear now. It may not rain this afternoon.
Diana is very tired. She might not join us for dinner.
The meaning of could not (couldn’t) is different from may not and might not. We use could not when we think something is impossible.
They could not (couldn’t) win. They are three points behind and the game ends in ten seconds.
(vs They may/might not win. The other team is much stronger.)
We form yes/no-questions and short answers with could like this:
Could I/you/we/they/he/she/it get on the bus?
Yes, I/you/we/they/he/she/it could. No, I/you/we/they/he/she/it could not / couldn’t.
For may and might, we usually use phrases like Do you think …? instead of May/Might …?.
Do you think we may/might get on the bus?
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In the Secondary 3 TSA writing tasks as well as in Paper 2 of the HKDSE exam, some students failed to use modal verbs correctly.
2014 S3 TSA Writing
Students should not went to school when there is a typhoon.
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We use the base form of the verb go after the modal verb should.2013 HKDSE Paper 2 Part A
Do not spend too much time on playing video games. We can spend more time on sports.
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We use the modal verbs should, ought to, have to or must to give advice.2016 HKDSE Paper 2 Part B Question 3
They perhaps learn a new language when they work in another city in Asia.
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We use the modal verbs may, might, could to talk about possibility.Do the Quiz below. Check your understanding of modal verbs.
Tick (✔) the correct answers.
1. You wash your hands before meals.
A. might B. must
2. Jennifer should more vegetables.
A. eat B. eats
3. We study harder in order to do better at school.
A. ought to B. may
4. You must not the fire.
A. touching B. touch
5. Kate has an exam tomorrow. She come to our party.
A. might not B. must not
6. James be more active and spend less time on online games.
A. may B. ought to
7. They go to the cinema if it rains.
A. might B. should
Exam Report
go
should
may
Quiz
✔
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Exercise 1
Complete the sentences using ‘must not’ or ‘have to’ and the words in the box.
wait drive slowly enter walk your dog pay
swim keep left ride a bicycle take photos
You here.
You here.
You
here.
You
here.
You
here.
You
on this road.
You
here.
You
here.
You
on this road.
A
D
G
B
E
H
C
F
I
must not enter have to pay
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!
!
Exercise 2
Complete the sentences by writing the letters (A–H) in the spaces provided.
1. You could get sunstroke if
2. You may have to pay a fine if
3. You might get a cold if
4. You may lose your friends if
5. You could lose your wallet if
6. You might forget your homework if
7. You may get tooth decay if
8. You could lose sleep if
C
A. you pack your schoolbag in a hurry.
B. you drink coffee late at night.
C. you don’t drink enough water during a hike.
D. you don’t zip up your bag.
E. you only wear that shirt in such weather.
F. you don’t brush your teeth twice a day.
G. you don’t keep your promises to them.
H. you cross the road at red lights.
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Exercise 3
Write sentences or questions using the modal verbs in brackets and the words given.
1. in order to enjoy the whole concert / we / arrive on time (must)
2. pay for lunch / they / not (have to)
3. we / three to five times a week / exercise (ought to)
4. in the cinema / we / use cameras / not (must)
5. Jason’s mobile phone / be / this / ? (could)
6. this summer / visit / in Canada / I / my cousin (may)
7. your phone / switch off / you / during the performance (have to)
8. go hiking / this weekend / Katy / with us / not (might)
9. take your rubbish / you / when leaving the country park / with you (should)
10. work / Mr Lee / on Saturdays / ? (have to)
11. eight glasses of water / every day / drink / we / ? (should)
12. Dad’s / be / these small shoes / not (could)
13. our friends / talk with / at the show / we / not (ought to)
14. if he is free / make us a cake / Alan (might)
We must arrive on time in order to enjoy the whole concert.
They don’t have to pay for lunch.
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Exercise 4
Read the conversation. Fill in the blanks by choosing one of the options in brackets.
James : Do you have any ideas for the project, Marco?
Marco : The guidelines say we (1) (have to / might) examine social problems in Hong Kong.
James : We (2) (ought to / might) talk about the ageing population. What do you think?
Marco : Good idea. But I am also interested in urban renewal. Our classmates (3) (must / may) be interested in it.
James : What’s urban renewal?
Marco : When a city gets old, it (4) (couldn’t / may not) be suitable for people to live in any longer. There (5) (must / might) be problems like a poor living environment, traffic jams, etc. Very often the government (6) (has to / may not) tear down old buildings to rebuild the city.
James : I see. I think Miss Fong has told us about that.
Marco : She has. You (7) (may / ought to) pay attention to what the teachers say.
James : You are right. I (8) (don’t have to / shouldn’t) be so absent-minded.
I (9) (must / might not) work harder.
Marco : Let’s get back to the project. So which topic do you prefer?
James : Shall we go ahead with urban renewal?
Marco : Sure. Do you know the deadline for the project?
James : We (10) (might / have to) hand in the project two weeks from now.
Marco : Then there isn’t much time left. We (11) (should / may) start as soon as possible.
Why don’t we work in the library after school today?
James : No problem.
have to
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Exercise 5
Read the article. Choose the best option to complete each blank and circle the correct letter.
1. A. must not consider B. may not consider C. should consider
2. A. must not miss B. may not miss C. could not miss
3. A. do not have to try B. should try C. could not try 4. A. may have
B. might have C. should not have
5. A. should make B. may make
C. ought not to make
6. A. ought to want B. must want C. may want 7. A. may not go
B. might go
C. do not have to go
8. A. must not do B. must do C. may do
9. A. could be B. might not be C. should be 10. A. should bring
B. could not bring C. do not have to bring
11. A. must feel B. could not feel C. might feel
If you have never been to HK, you (1) paying a visit.
Let’s start with food. You (2) milk tea and egg tart. They are Hong Kong people’s favourite and do not cost too much. A cup of milk tea and an egg tart make the best afternoon tea set. Another food that you (3) is roast goose. There are two world-famous roast goose restaurants in Wan Chai. Do check them out.
Hong Kong is also a paradise for shopping. There are branded goods as well as cheap items, so you (4) a problem finding what you want. Mong Kok, Tsim Sha Tsui and Causeway Bay are all famous shopping areas. You (5) sure you visit at least one of them.
For those who love outdoor activities, you (6) to bring your hiking shoes. Hong Kong has various hiking trails that are close to the city centre. Travellers who get up early
(7) hiking in the morning and, after a shower, you (8) other activities, such as visiting museums, watching performances, etc.
If you visit Hong Kong in summer, be careful with the temperature indoors and outdoors.
Many indoor areas are air-conditioned and the temperature (9) quite low.
You (10) a scarf or a cardigan with you. If you come to Hong Kong in winter, bring enough warm clothes. Since there is no central heating in Hong Kong, you (11) cold even when you are indoors.
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Wrap-up
Read the following letter of advice. There are eleven mistakes altogether, including the example. Underline the mistakes. Write the correct answer above the mistake.
Dear Joyce,
Thank you very much for your letter. I think you worry too much about your weight.
All you need is a more active life. Then you will have many friends.
Your weight is normal so you must to stop going on diets. However you ought add more fruit and vegetables to your meals so that there is enough fibre and vitamins.
You should has two portions of fruit and vegetables every meal. You ought to not drink so little water. Drink at least eight glasses of water every day. When you follow a more healthy diet, you ought feel more energetic and positive. You could having better skin too.
Your interpersonal relationships have nothing to do with your appearance. The only problem you have is that you are too shy. What you could to do is to join some extra-curricular activities. They could created opportunities for you to meet more people and talk with them. For example, you may joining the Science Club, where you have work with other people to solve problems.
You are a kind and friendly person. You really should not to question yourself.
Love, Elsa
must stop
Write a short letter of advice to a friend on having a healthy lifestyle. Write about 100 words.
Hint: Try to use modal verbs to give advice or talk about necessity and possibility.
You try
