MUST, HAVE TO, SHOULD (OBLIGATION)

Modal Verbs of Obligation

We can use have to + infinitive, must + infinitive and should + infinitive to express obligation (something you have to do).

Present	Positive	Negative
have to / don’t have to	strong obligation (possibly from outside) Children have to go to school. (sometimes ‘have got to’)	no obligation I don’t have to work on Sundays. You don’t have to eat anything you don’t like.
must / mustn’t	strong obligation (possibly based on the speaker’s opinion) I must study today.	negative obligation You mustn’t smoke here.
should / shouldn’t	mild obligation or advice You should save some money.	mild negative obligation or advice You shouldn’t smoke so much.

Be careful about the difference between mustn't and don't have to!
Mustn't means it's not allowed, or it's a bad idea:

• You mustn't eat so much chocolate, you'll be sick

Don't have to means you don't need to do something, but it's fine if you want to do it:

• I don't have to get up early at the weekend
  (of course, if I want to get up early, that's fine, but I can stay in bed if I want

Past	Positive	Negative
had to / didn’t have to	obligation in the past I had to go to wear a school uniform when I was a child.	no obligation in the past We didn’t have to go to school on Saturdays.
must*	changes to 'had to'	-
should have + pp / shouldn’t have + pp	a past action which didn’t happen: the advice / regret is too late You should have gone to bed earlier, now you have missed the train.	a past action which didn’t happen: the advice / regret is too late You shouldn’t have taken that job., it was a bad idea.

* Remember ‘must have done’ is a modal verb of deduction or speculation, not obligation in the past. For example: Julie must have left. Her coat’s not here.


EXERCISE ONE
EXERCISE TWO
EXERCISE THREE

COMPARATIVE AND SUPERLATIVE ADJECTIVES

Forming Comparative and Superlative Adjectives. from eflnet.com

One-syllable adjectives.

Form the comparative and superlative forms of a one-syllable adjective by adding –er for the comparative form and –est for the superlative.

One-Syllable Adjective	Comparative Form	Superlative Form
tall	taller	tallest
old	older	oldest
long	longer	longest

• Mary is taller than Max.
• Mary is the tallest of all the students.
• Max is older than John.
• Of the three students, Max is the oldest.
• My hair is longer than your hair.
• Max's story is the longest story I've ever heard.

If the one-syllable adjective ends with an e, just add –r for the comparative form and –st for the superlative form.

One-Syllable Adjective with Final -e	Comparative Form	Superlative Form
large	larger	largest
wise	wiser	wisest

• Mary's car is larger than Max's car.
• Mary's house is the largest of all the houses on the block.
• Max is wiser than his brother.
• Max is the wisest person I know.

If the one-syllable adjective ends with a single consonant with a vowel before it, double the consonant and add –er for the comparative form; and double the consonant and add –est for the superlative form.

One-Syllable Adjective Ending with a Single Consonant with a Single Vowel before It	Comparative Form	Superlative Form
big	bigger	biggest
thin	thinner	thinnest
fat	fatter	fattest

• My dog is the biggest of all the dogs in the neighborhood.
• Max is thinner than John.
• Of all the students in the class, Max is the thinnest.
• My mother is fatter than your mother.
• Mary is the fattest person I've ever
• My dog is bigger than your dog.

Two-syllable adjectives.

With most two-syllable adjectives, you form the comparative with more and the superlative with most.

Two-Syllable Adjective	Comparative Form	Superlative Form
peaceful	more peaceful	most peaceful
pleasant	more pleasant	most pleasant
careful	more careful	most careful
thoughtful	more thoughtful	most thoughtful

• This morning is more peaceful than yesterday morning.
• Max's house in the mountains is the most peaceful in the world.
• Max is more careful than Mike.
• Of all the taxi drivers, Jack is the most careful.
• Jill is more thoughtful than your sister.
• Mary is the most thoughtful person I've ever met.

If the two-syllable adjectives ends with –y, change the y to i and add –er for the comparative form. For the superlative form change the y to i and add –est.

Two-Syllable Adjective Ending with -y	Comparative Form	Superlative Form
happy	happier	happiest
angry	angrier	angriest
busy	busier	busiest

• John is happier today than he was yesterday.
• John is the happiest boy in the world.
• Max is angrier than Mary.
• Of all of John's victims, Max is the angriest.
• Mary is busier than Max.
• Mary is the busiest person I've ever met.

Two-syllable adjectives ending in –er, -le, or –ow take –er and –est to form the comparative and superlative forms.

Two-Syllable Adjective Ending with -er, -le, or -ow	Comparative Form	Superlative Form
narrow	narrower	narrowest
gentle	gentler	gentlest

• The roads in this town are narrower than the roads in the city.
• This road is the narrowest of all the roads in California.
• Big dogs are gentler than small dogs.
• Of all the dogs in the world, English Mastiffs are the gentlest.

Adjectives with three or more syllables.

For adjectives with three syllables or more, you form the comparative with more and the superlative with most.

Adjective with Three or More Syllables	Comparative Form	Superlative Form
generous	more generous	most generous
important	more important	most important
intelligent	more intelligent	most intelligent

• John is more generous than Jack.
• John is the most generous of all the people I know.
• Health is more important than money.
• Of all the people I know, Max is the most important.
• Women are more intelligent than men.
• Mary is the most intelligent person I've ever met.

Exceptions.

Irregular adjectives.

Irregular Adjective	Comparative Form	Superlative Form
good	better	best
bad	worse	worst
far	farther	farthest
little	less	least
many	more	most

• Italian food is better than American food.
• My dog is the best dog in the world.
• My mother's cooking is worse than your mother's cooking.
• Of all the students in the class, Max is the worst.

Two-syllable adjectives that follow two rules. These adjectives can be used with -er and -est and with more and most.

Two-Syllable Adjective	Comparative Form	Superlative Form
clever	cleverer	cleverest
clever	more clever	most clever
gentle	gentler	gentlest
gentle	more gentle	most gentle
friendly	friendlier	friendliest
friendly	more friendly	most friendly
quiet	quieter	quietest
quiet	more quiet	most quiet
simple	simpler	simplest
simple	more simple	most simple

• Big dogs are gentler than small dogs.
• Of all the dogs in the world, English Mastiffs are the gentlest.
• Big dogs are more gentle than small dogs.
• Of all the dogs in the world, English Mastiffs are the most gentle.
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