Learning is a treasure that will follow its owner everywhere.

I. Different forms of Modals:

a) The positive form of modals is: Modal + bare infinitive

- I must see you tomorrow.

- We have to go now.

b) The negative form of modals is: Modal + not + bare infinitive

- You should not go to bed so late.

- They needn’t come if they don’t want to.

c) The interrogative form of modals is: Modal + subject + bare infinitive

- Can you help?

- Will she be here soon?

d) Short answers: Yes/no + subject + modal

- Yes, we can

- No, she will not

e) In active and passive forms:

II. Usages of modal auxiliaries:

We can use modals to express many functions: ability, possibility, deduction, obligation, necessity, permission, request, advice, offer, suggestion or invitation … etc.

II. 1. Expressing ability: Can / Could / Be able to

a) We use can (present/future) could (past) to refer to a general ability.

- She can sing really well.

- I can come and see you next week.

- He could read when he was four.

b) We use to be able to for different grammatical forms that are impossible with can.

- I like being able to work at home.

- I have been able to work faster since I got my computer.

II. 2. Expressing possibility: May / Might / Could+B-I

a) We use May / Might / Could + Bare-Infinitive to express possibility in the present.

- “where is Tom?” – “I don’t know. He may be outside”

- “whose pen is it?” – “It could be Doudou’s”

b) We use May / Might / Could have + p.p to express possibility in the past.

- I don’t know why they were late. I suppose they could have lost.

- She wasn’t at the party last night. She might have been feeling too tired to come.

c) If you want to say that something is possible, you use: can/may be + p.p or also may/might + infinitive.

- Stamps can/may be bought at most shops.

- I may /might see you next week.

II. 3. Expressing deduction: Must / Can’t+B-I

a) In the present, we use Must (positive) and (negative).

- Jane is not at home. So she must be on the way here.

- He can’t be driving here. He hasn’t got a driving license

b) In the past: Must/can’t have+p.p.

- He can’t have forgotten about the meeting: He talked to me about it only this morning.

- You must have been talking on the phone for a long time. I phoned you four times and it was engaged.

II. 4. Expressing obligation: Must / Mustn’t / Have to (present) Had to (past).

NB: Have to and must are interchangeable but there is a slight difference between them.

Have to (the obligation is external)

Must (the obligation comes from the speaker / speaker)

- We have to get up early tomorrow to catch the plane.

- We must get up early tomorrow. We have got a lot to do.

Remark: mustn’t = for prohibition.

- You must not smoke here.

II. 5. Expressing necessity: Need

a) Most of the time it is used in a question or negative statement.

- You needn’t come if you don’t want to.

- Need I bring anything with me?

NB: Need as an ordinary verb is followed by (to).

- You don’t need to come if you don’t want to.

- Do I need to bring something with me?

II. 6. Expressing permission and request:

a) Asking permission

Can

Could

May             I…?

Might

- “Can I borrow your pen, please?”. - “Yes, of course you can”

- “Do you think I could leave my bag here?” - “Yes, certainly”

- “May I use your phone, please?”.  - “Yes, of course you may”

b) Asking for a request

Can

Could         you…?

Would

- Could you open the door for me please?

- Would you mind + gerund…?

- ………………..... + If I + verb?

Would you mind opening the windows?

……………….. if I open the windows?

II. 7. Giving advice: Should / Ought to

a) Should and ought to (present / future) show that the action would be a good idea, it would be the best thing to do.

- You should / ought to try and lose weight.

b) we use should and ought to with ( I think…., Do you think….?, Don’t you think…?)

- Don’t you think you should stop seeing him?

c) in the past, we use should / ought to + have + p.p

- I should have stayed at home.

- You shouldn’t have said that.

II. 8. Making suggestion or invitation.

Shall we…? We could…? Would you like to…?

- Shall we go out for a meal tonight? – “Yes, that would be nice”

- “We could have a game of tennis this afternoon” – “Yes, why not”

- “Would you like to come round tomorrow?” –“Yes, I would”

Practice 1: use the most appropriate modal

1- It must be late as it's already dark. It can't be any earlier than 5 PM. — pour impossibilité

2- Pupils may go out if they've finished their homework. Since your homework isn't in fact finished you may not go out. — refus de permission

3- "He can't be serious; no one could believe that." "In fact he's an important scientist, so he must be serious after all." — conclusion logique => nécessité

4- "She might get good results if she tries harder." "No, it's too late; the exam's next week: she can't possibly succeed." — impossibilité

5- If you want to ask for permission, use "can" or " may ". — pour demander la permission

6- My parents said "You must tidy your room", so I have to do it. — le sujet n'est pas à l'origine de l'obligation, donc 'have to' et non pas 'must'

7" might " is a little bit politer than "may". — le prétérit de 'may', 'might', est plus poli (d'ordinaire trop poli)

8- That must be right; your argument is perfectly logical! — conclusion logique => nécessité

9- If the figure has more than three sides, it can't be a triangle. — impossibilité

10- Since it's not forbidden by the rules, I suppose we may do it. — permission