MODAL VERBSMust, have to, should, need to

MUST + infinitive (must do/must work, etc)

I must (do something) = I need to to it.

It’s a fantastic film. You must seeit.

Musn’t (= must not) = it is necessary NOT to do it, it is the wrong thing to do.

You musn’t play football here. She musn’t take her mom’s lipstick.

Need to + infinitive (need to go/need to talk, etc)

They need to do exercise. It’s good for them.

Need to (do something) = it is necessary to (do something)

Don’t need to (do something) = it is not necessary.

You don’t need to touch it if youdon’t want.

She doesn’t need to wear heranorak, it isn’t cold.

Mustn’t vs don’t need to

You musn’t eat so many sweets. You don’t need to eat more ifyou are full.

SHOULD + infinitive (should do/should watch, etc)

- You should do something = it is a good thing to do, it is the right thing to do.

- When you play tennis, you should always watch the ball.

- You shouldn’t do something = it is not a good thing to do.

- You watch TV all the time. You shouldn’t watch TV so much.

Don’t need to (do something) = it is not necessary.

Tom doesn’t study enough. He should study harder.

Tom shouldn’t go to bed so late.

Must vs Should

Must is stronger than Should

• It’s a good film. You should go and see it. (it’s a good thing to do)

• It’s a fantastic film. You must goand see it. (you can’t miss it)

Questions

• Present: do/does

• What time do you have to go to the

dentist tomorrow?

• Does she have to work on Saturday?

• Past: did

• Why did they have to leave the school

early?

Negatives

• Present: don’t have to/doesn’t have to

• I’m not working tomorrow, so I don’t have to

get up early.

• Jane doesn’t have to work on Saturdays.

• Past: didn’t have to

• We didn’t have to wait very long for the bus –

it came in a few minutes.

Have to + infinitiveI have to do something = it is necessary for me to do it, I am obliged to do it.

Must and have to

When you are not giving your personal opinión, use have to

(not must). Compare:

o Jane won’t be at work this afternoon. She has to go to the

doctor. (it is a fact – this isn’t my personal opinión)

o Jane isn’t well. She doesn’t want to go to the doctor, but I told

her she must go. (this is my personal opinión)

You can use must or have to when

you say what YOU think is necessary,

when you give YOUR opinión:

- It’s a fantastic film.

You must see it.

or

You have to see it.