OBLIGATIONOBLIGATION

HAVE TO HAVE TO : : Impersonal ObligationImpersonal Obligation

It’s a external rule or law.It’s a external rule or law.

MUST:MUST: Personal Obligation

It’s internal rule, decision or opinion

I have to mop the floor

You must mop the floor right

now!

To mop the floor is…The stepmother’s decision

You must must mop the floor right now!

Cindirella just follows the order

I have to have to mop the floor

HAVE TO in affirmative formHAVE TO in affirmative form

Present: Present:

HAVE TO

I, you, they, weHAS TO

He, she, it

Past:Past:HAD TO

I, you, they, we, he, she, it

Future:Future:

WILL HAVE TO

MUST:

MUST I, you, he, she, it, we, they

MUST in affirmative formMUST in affirmative form

MUST is only used in the the present time present time , for the other tenses we use HAVE TO

To express Possibility:MUST + HAVE + PAST HAVE + PAST PARTICIPLE PARTICIPLE

To express Obligation: The past of MUST is

HAD TO HAD TO

She must have cleaned must have cleaned the house yesterday

She had to had to clean the house yesterday

You had to clean all the house

You must clean all the house !

The Negative form of The Negative form of MUST & HAVE TO MUST & HAVE TO

When we use the negative form, the meaning is totally different

PROHIBITION UNNECESITY

HAVE TO AND MUST IN THE NEGATIVEHAVE TO AND MUST IN THE NEGATIVEMUST:

MUST NOT

(MUSTN’ T)

Negative Forms!every grammatical

person.

HAVE TO:Present: Present: Don’t have to

Doesn’t have to

Past:Past:Didn’t have to

Future:Future:Won’t have to

I / we/ you/ they

She/ he / it

Every grammatical person

PROHIBITIONPROHIBITION

You must not go to the party.

Going to the party is Going to the party is prohibited.prohibited.

LACK OF NECESSITYLACK OF NECESSITY

You don’t have todon’t have to cry. We will help you.

It’s not It’s not necessary to cry.necessary to cry.

•You mustn’t go. It’s an order (Don’t go)(Don’t go)

•You don’t have to go, but you can if you want to.

(It’s not necessary)(It’s not necessary)

COMPARE:COMPARE:

You _________ do

your homework

I _________ domy homework

MUSTMUST

HAVE HAVE TOTO

It’s late…I ____ go home…I don’t want

miss the dinner

MUSTMUST

Be quiet!You ________

make noiseMUSTN’TMUSTN’T

We _________ get home

early. Mum wants us

before the dinner

HAVE TOHAVE TO

You _________ clean the kitchen.

I’ve already done it.

DON’T HAVE DON’T HAVE TOTO

To be honest… I think you _______

change your boyfriend

MUSTMUST

I like wearing jeans and

t-shirts , but in the office I

__________

wear formal clothes

HAVE TOHAVE TO

I am overweight . I ________

do exercises everyday.

MUSTMUST

You _________ bring your dog here.

MUSTN’MUSTN’TT

I’m on my holidays so I _________ worry about anything…There’s no

need to do it.

DON’T HAVE DON’T HAVE TOTO

Ok! I get it.I don’t need your help…

You ___________

be here…DON’T HAVE DON’T HAVE

TOTO

BYE