General RevisionModal Verbs

What are modal verbs?

• Modals (also called modal verbs, modal auxiliary verbs, modal auxiliaries) are special verbs which are different from normal verbs like "work, play, visit...“

• They give additional information about the function of the main verb that follows it.

Use of modal verbs:

• Express functions such as:• Permission• Ability• Obligation• Prohibition

• Lack of necessity• Advice• possibility• probability

Modal verbs are followed by an infinitive without "to“:

Examples:• You must stop when the traffic lights turn red.• You look awful! You should see a doctor.

• Exception:• You ought to go to the doctor.

Modal Verb Meaning Expressing Example

must

to have to 100 % obligation I must stop when the traffic lights turn red.

to be very probable logical conclusion (deduction)

He must be very tired after such enormous work

must notnot to be allowed to

prohibition You must not smoke in the hospital.

can

to be able to ability I can swim

to be allowed to permission Can I use your phone please?

it is possible possibility Smoking can cause cancer !

could

to be able to ability in the past When I was younger I could stay up all night and not get tired..

to be allowed to more polite permission

Excuse me, could I just say something?

it is possible possibility It could rain tomorrow!

mayto be allowed to permission May I use your

phone please?it is possible, probable

possibility, probability

It may rain tomorrow!

might

to be allowed to more polite permission

Might I use your phone please?

it is possible, probable

weak possibility, probability

I might come and visit you in America next year, if I can save enough money.

Modal Verb Meaning Expressing Example

neednecessary necessity Need I say more?

need notnot necessary lack of

necessity/absence of obligation

I need not buy any tomatoes. There are plenty in the fridge.

should/ought to

used to say or ask what is the correct or best thing to do

50 % obligation I should / ought to see a doctor. I have a terrible headache.

to suggest an action or to show that it is necessary

advice You should / ought to revise your lessons

to be very probable logical conclusion (deduction)

He should / ought to be very tired after such enormous work

had betterto suggest an action or to show that it is necessary

advice You 'd better revise your lessons

GOLDEN RULES ABOUT MODAL VERBS

• Modal verbs never add an -s in the third person singular: – He must work harder to pass his exams

• Modal verbs don’t need auxiliaries to make negative sentences or questions: – Should I apologise?– I mustn´t smoke in hospitals

• Modal verbs only have one form. You need other verbs to express the same thing in the past, future etc.– I´ve been able to finish on time.

EXPRESSING ADVICE

• We use should and ought to to express advice or make recommendations:You should eat less fat if you want to lose weight.

• You ought to relax if you don´t want to get ill.• You shouldn´t be rude to anybody.• You oughtn´t to tell lies.

EXPRESSING OBLIGATION OR NO OBLIGATION

• We use must and have to to express obligation.

• The difference between them is: We use must when the obligation is inside the speaker. It is a moral obligation.

• We use have to when the obligation is outside the speaker. It comes from the situation.

EXPRESSING OBLIGATION OR NO OBLIGATION

• I must do some exercise to get fit.• We have to be quiet in class. That’s the rule.

Note: Have to is not a modal verb.

We use don’t / doesn’t have to, needn’t and don’t /doesn’t need to to express no obligation.

• You don’t need to get up early. It is Sunday!• She doesn’t need to wear a coat. It is warm outside.• She needn’t cook tonight. We´re eating out.

EXPRESSING PROHIBITION

We use mustn’t to express prohibition.

• Children under 16 mustn’t go in there. At school we mustn’t smoke.