Look at the sentences Marge says

- My cousin, who is only 2 years old, can already speak.

- Can your sister play the piano?

- Messi can play football very well.

- Let’s buy some Chinese food. I can’t cook very well.

- My uncle, who is a chef, is able to prepare delicious dishes.

- If you save money, you will be able to buy a new car.

- When I was four years old, I could read and write.

- Sarah’s grandmother could sing very well.

-My cousin couldn’t swim until last year and now she can swim better than me.

- Can you pass me the salt, please? (REQUEST)

- Can I come in? (ASK FOR PERMISSION)

- Ok, you can go now. (GIVE PERMISSION)

- Could you help me with this exercise? It’s so difficult.

COULD is also used to make a polite suggestion.A: I’m going to Holland next week.

B: Oh, really? You could visit your Dutch relatives then.

- Mrs. Lola, may I go to the toilet?

- Will you help me with the suitcases, please? They’re so heavy.

- Would you open the window, please? It’s so hot in here.

- Shall I help you with your luggage?

- Would you like a sandwich?

- Students in private schools must wear a uniform. (RULE)

- All of our friends are going to that party. We must go too. (NECESSITY)

The obligation

comes from the speaker

The obligation

doesn’t come from the speaker

MUM: You must be home by 11 o’clock.

You go out. When it’s time to go, you can say:

“I’ll leave. I have to stay home by 11 o’clock.”

They have more or less the same meaning but…

HAVE TO is used for all the forms MUST doesn’t have. Moreover, HAVE TO is used in the interrogative sentence.- Do you have to go right now?

- Yesterday I had to do the washing because the washing-machine broke down.

- If you want to be successful, you will have to work very hard.

Prohibition No obligation, no necessity

-You mustn’t smoke in the premises. (IT IS PROHIBITED, IT IS NOT ALLOWED)

- You don’t have to wear a uniform at school. (IT IS NOT NECESSARY)

-She needn’t bring anything; there’s lots of food.

-She doesn’t have to bring anything; there’s lots of food.

- It’s 8 o’clock. Sally must be at work. (I’M SURE)

- It’s 8 o’clock. Sally can’t be at home. (IT’S IMPOSSIBLE)

-Advice

-Opinion

-Moral duty

-You ought to improve your manners.

- I think you should tell him the truth.

- Carol should visit her grandfather more often.

Scissors can be dangerous if not used properly.

I may go to the party.

(I’m not sure, it’s possible)

I might go to the party.

(I’m not sure, it’s improbable)