You have to be tall if you want to be a basketball player.

You mustn't tell anybody. It's top secret!

You needn't shout! I'm not deaf!

They don't have to go shopping today.

a-It is used to express absence of obligation. Although it is the negative of “have to”, it is never used to express prohibition like “mustn't”.

b-To express absence of obligation in the past we use” didn't have to”.

__ She doesn't have to finish the book till next week.

__ I didn't have to buy a new dress for the party.

__ I don't have to go to school today.

a-It's used to express absence of obligation (about the present or the future)

b-When followed by “have + past participle it is used to talk about absence of obligation in the past.

__ You needn't wear a tie. It's optional.

__ We needn't have bought so many biscuits.

__ Our teacher says we needn't bring the textbooks tomorrow.

a-Expressing prohibition.

b-Expressing strong recommendation

( should is often used instead)

Remember that “mustn't” is used to express prohibition in the present, for prohibition in the past we use “not allow” or “not let”. My parents didn't allow me to go to parties or my parents didn't let me go to parties.

__ You mustn't be so rude to people.

__ We mustn't fish in this river.

a-It expresses present/future obligation but it is less strong than “must”.

b-It also expresses past obligation

c-It's also used to express certainty, when we are sure about something.

__ Frank has to be as clever as his brother.

__ They had to do the exam again because they had cheated.

__ She has to go to the dentist.

a-Talking about present or past possibility/impossibility.

b-Talking about past ability/inability.

c-Making polite requests.

d-Asking for permission.

e-Used in 2^nd and 3^rd conditionals.

__ I'd send him a card if I could buy one.

__ Could I borrow your dictionary?

__ I could swim when I was five.

__ Could you open it for me, please?

__ They could be at home by now.

Could you ride a bike when you were a child?

a-Expressing obligation.

b-Making deductions about the present.

c-Making deductions about the past.

d-Giving advice (should is often used instead)

__ She must have missed the bus.

__ You really must read this book.

__ They must be very happy after passing their final exams.

__ They must finish the project by the end of this week.

You must do your homework every day.

a-Talking about general ability.

b-Asking or giving permission.

c-Request something

d-Making offers

e-General possibility

__ You can get lost without a map.

__ Now you can open your books.

__ Can you lend me some money?

__ Can I help you dry the dishes?

__ My dad can run faster than me.

He can play the piano very well.

a-Talking about general inability.

b-Refusing permission.

c-Request something

d-Making present deductions

e-Making past deductions

__ She can't have broken the vase.

__ He can't be Peter. He's in Paris now.

__ Can't you speak louder, please?

__ I can't speak any foreign languages.

__ Sorry, you can't go out now.

He can't read. He can't be very clever.

You have to be tall if you want to be a basketball player.

You mustn't tell anybody. It's top secret!

You needn't shout! I'm not deaf!

They don't have to go shopping today.

a-It is used to express absence of obligation. Although it is the negative of “have to”, it is never used to express prohibition like “mustn't”.

b-To express absence of obligation in the past we use” didn't have to”.

a She doesn't have to finish the book till next week.

b I didn't have to buy a new dress for the party.

a I don't have to go to school today.

a-It's used to express absence of obligation (about the present or the future)

b-When followed by “have + past participle it is used to talk about absence of obligation in the past.

a You needn't wear a tie. It's optional.

b We needn't have bought so many biscuits.

a Our teacher says we needn't bring the textbooks tomorrow.

a-Expressing prohibition.

b-Expressing strong recommendation

( should is often used instead)

Remember that “mustn't” is used to express prohibition in the present, for prohibition in the past we use “not allow” or “not let”. My parents didn't allow me to go to parties or my parents didn't let me go to parties.

b You mustn't be so rude to people.

a We mustn't fish in this river.

a-It expresses present/future obligation but it is less strong than “must”.

b-It also expresses past obligation

c-It's also used to express certainty, when we are sure about something.

b Frank has to be as clever as his brother.

c They had to do the exam again because they had cheated.

a She has to go to the dentist.

a-Talking about present or past possibility/impossibility.

b-Talking about past ability/inability.

c-Making polite requests.

d-Asking for permission.

e-Used in 2^nd and 3^rd conditionals.

e I'd send him a card if I could buy one.

d Could I borrow your dictionary?

b I could swim when I was five.

c Could you open it for me, please?

a They could be at home by now.

Could you ride a bike when you were a child?

a-Expressing obligation.

b-Making deductions about the present.

c-Making deductions about the past.

d-Giving advice (should is often used instead)

c She must have missed the bus.

d You really must read this book.

b They must be very happy after passing their final exams.

a They must finish the project by the end of this week.

You must do your homework every day.

a-Talking about general ability.

b-Asking or giving permission.

c-Request something

d-Making offers

e-General possibility

e You can get lost without a map.

b Now you can open your books.

c Can you lend me some money?

d Can I help you dry the dishes?

a My dad can run faster than me.

He can play the piano very well.

a-Talking about general inability.

b-Refusing permission.

c-Request something

d-Making present deductions

e-Making past deductions

e She can't have broken the vase.

d He can't be Peter. He's in Paris now.

c Can't you speak louder, please?

a I can't speak any foreign languages.

b Sorry, you can't go out now.

He can't read. He can't be very clever.

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