1. MODAL VERBS
A modal is a type of auxiliary (helping) verb that is used to express: ability, possibility, permission or obligation. Modal phrases (or semi-modals) are used to express the same things as modals, but are a combination of auxiliary verbs and the preposition to. The modals and semi-modals in English are:
Can/could/be able to 4. Must/have to
May/might Will/would
Shall/should

3. Can/could/be able to Can
Is used to talk about possibility. e.g. ‘Can you meet me at 5?’
Is used to talk about ability. e.g. ‘I can ride a bike.’
Is used to make informal requests and orders. e.g. ‘Can you bring me my jumper?’
Has two negative forms, can’t and cannot.

4. Could
Is used to talk about past abilities. e.g. ‘When I was a child I could do handstands.’
Is used to make formal requests. e.g. ‘Could you fax me that document by Tuesday?’
In the negative form, is couldn’t.

5. Be able to Be able to Is sometimes used instead of can or could.
Can be used with all tenses. e.g. ‘I will be able to see you next week.’
Is used to talk about ability. e.g. ‘Are you able to write formal letters?’

6. May /Might
We can use 'may' to ask for permission. However this is rather formal and not used very often in modern spoken English
May I borrow your pen?
May we think about it?
May I go now?

7. We use 'may' to suggest something is possible
It may rain later today.
I may not have time to do it today.
Pete may come with us

8. might
We use 'might' to suggest a small possibility of something. Often we read that 'might' suggests a smaller possibility that 'may', there is in fact little difference and 'might is more usual than 'may' in spoken English.
She might be at home by now but it's not sure at all.
It might rain this afternoon.
I might not have time to go to the shops for you.
I might not go.

9. Shall Shall – to make a suggestion Shall we dance? Shall I go now?
Shall for obligation in very formal situations
You shall obey the rules.
Students shall not enter here.
There shall be no food and drink on the premises.

10. Should is often used to give an opinion, to make a suggestion,
express a preference or an idea.
You should stay at home if you are feeling tired.
I should walk to work.
He should be more open to ideas.

11. Should – to ask for an opinion.
Should we tell him about our idea?
What should we do now?

12. Will Will Will is used to show desire, preference, choice or consent:
I will accept your offer.
Will you please be quiet?

13. Will To show the future:
It will be a great party. I will probably go out tonight.

14. This bottle will hold two litres of wine
To express capability:
The ship will take three hundred guests.
This bottle will hold two litres of wine
To express determination or insistence:
I will pass my driving test.
I will do as you say.

15. Would Would – used to show preference
I would rather go to the cinema today.
(I prefer going to the cinema today.)
Would – to show a wish
I would like to have more free time.
Would – for advice
If I were you, I would study economics.

17. Would Rather & Had Better
After would rather, we use the infinitive without to.
I would rather stay at home than go to a movie.
It means (I prefer staying at home)
I would rather leave. (I would like to leave.)

18. Contracted Would - I'd, He'd, She'd, We'd, You'd, They'd
She'd rather stay with me than go out with you.
They'd rather play with the baby than change its diaper.

19. Had Better
We use had better when we give advice to others. The meaning of had better is similar to should. Had better expresses advice and warning.
You had better watch your steps.
She had better listen to you.
It's getting late. I had better go.

20. Contracted form of had better - I'd better, You'd better…
Notice that the contracted forms of had and would are the same and that I'd can be I had or I would so we need to look at the context to see what's meant to be said.
I'd rather lie than to hurt you. (I would)
I'd better tell the truth. (I had better)

21. should/ought to/had better
There are three auxiliary verbs that you can use to give advice. They are should, ought to, and had better.
You should put cool water on a burn.
You ought to put cool water on a burn.
You had better put cool water on a burn.

22. Although all three have the meaning of should, "had better" is stronger because it implies a negative consequence if you don't follow the advice. Another difference is that usually ought to and had better are not used with questions.
Should I put cool water on a burn?
Ought I to put cool water on a burn?
Had better I put cool water on a burn?
There is a difference in the negative form as well. You can make a contraction only with the verb should, not the other two (see examples below). Also, note the position of the word not in the negative sentence below. The word not goes after should and had better but in the middle of ought to ("ought not to").

23. There is a difference in the negative form as well
There is a difference in the negative form as well. You can make a contraction only with the verb should, not the other two (see examples below). Also, note the position of the word not in the negative sentence below. The word not goes after should and had better but in the middle of ought to ("ought not to").
Negative Sentence
Contraction
You should not put hot water on a burn.
You shouldn't put hot water on a burn.
You ought not to put hot water on a burn.
(There is no contraction.)
You had better not put hot water on a burn.

26. Type rather or better into the box. would rather, had better
Exercise
Type rather or better into the box. would rather, had better
You ………………………………. stay here until the storm passes.
I……………………..work outside than have to be in an office
all day.
Would you ………………………wait until you've had longer to think about it?
We …………………..not ring them now. They're probably putting the baby to bed.
I ……………………….. have a window seat, please.
You …………………….. stay in and study tonight. You've got a test tomorrow.
had better
would rather
would rather
had better
would rather
had better

27. shouldn’t / ought not to
Should (not) / ought (not) to / had better (not)
1. You ……………………………….. to take him to the emergency room.
2. …………………………………...I put on a bandage?
3. They ………………………… not hurt his injury.
4. We ………………………………… hurt him.
5. You ………………………………… do abdominal thrusts.
ought
Should
had better/ should
shouldn’t / ought not to
shouldn’t / ought not to