1. Present and future2. Past3. Exercises

1.ABILITY: Can and Be able to-Can: ability

Ex: I can swim.-Be able to is used in situations where can does

not have the necessary grammatical form.Ex: I’d like to be able to swim.

2. CERTAINTY and UNCERTAINTY:

-Must and can’t: make deductions, when we are more and less certain about something.

Ex: You must be tired after your journey .(I suppose you are)

That can’t be Sue. She’s in Brazil. (I’m sure it’s impossible)

-May and might: express uncertainty or possibility. Might is less likely than may.

Ex: It may not rain. I might go out. I don’t know.

2. CERTAINTY and UNCERTAINTY:

-Be bound to: refers to the future, whereas must refers to the present.

Ex: You’re bound to see Paula if you go there.You must see Paula if you go there.

3.OBLIGATION:

-Must and have to:+Have to: describes obligations made by someone else.Ex: you have to turn left here. (It’s the law)+Must: a personal obligation.Ex: You must start working harder! ( I say so)

3.OBLIGATION:

-Mustn’t and don’t have to:+Mustn’t: describes something which is not allowed.Ex: You mustn’t leaves any bags here. (It’s against the rules)+Don’t have to: something which is not necessary.Ex: You don’t have to apply yet. (It’s not necessary)

- Should and ought to: have the same meaning; describe ‘what is good idea’ and can be used to give advice, or polite instructions.Ex: I think you should see a doctor.

You ought not to continue.

-Should: describes actions we expected to happen.Ex: Brenda should be home by now. (She is expected to be)

-Is/ Are to: used in formal instructions.Ex: No-one is to leave the room.

You are not to leave the room.

-Had better: refers present or future time and give advice how to stop something going wrong.Ex: I think you’d better leave now. (before it’s too late)

You’d better not drive. (It’ might be dangerous)

- Could: describes past abilityEx: When I was young, I could run

very fast.

- Could and Was able toWas able to describes the ability to

successfully complete an actionEx: Mary was able to help us. (She

actually helped us) Mary could help us. (But perhaps she didn’t)

-Must have and Can’t have: used to make deductions about past actions.The “have” form does not change.

Ex: I must have left my wallet in the car. (I am sure I did). Jim can’t have noticed you. (I am sure he didn’t).

- May have, Might have and Could have: express possibility or uncertainty about past actions.The “have” form does not change.

Ex: Jean might have missed the train. (Perhaps she did)He may not have received the letter. (Perhaps he didn’t)You could have been killed! (It was a possibility)

- Was/Were to be: describes something which was supposed to happen, but didn’t. It is formal in use. The “have” form does not change.

Ex: He was to have left yesterday.(He was supposed to leave, but he didn’t)

- Had toHad to is generally used as the past form of mustEx: Sorry I’m late, I had to take the children to school.The question form is Did you have to?Ex: Did you have to work late yesterday?

- Should have or Ought to haveThese express the speaker’s feeling that a mistake was made.

The “have” form does not change.Ex: You should have posted the letter yesterday.

(You made a mistake)You shouldn’t have told me the answer.(You were wrong)

- Needn’t have or Didn’t need toNeedn’t have describes an action which happened, but was

unnecessary. The “have” form does not change.Ex: I needn’t have bought more sugar.

(I did, but we have enough)I didn’t need to buy more sugar.(I didn’t, because we had enough)