Modals and Semi-Modals

A modal is a type of auxiliary (helping) verb that is used to express: ability, possibility, permission or obligation. Modal phrases (or semi-modals) are used to express the same things as modals, but are a combination of auxiliary verbs and the preposition to. The modals and semi-modals in English are:

1. Can/could/be able to

2. May/might

3. Shall/should

4. Must/have to

5. Will/would

Can, Could, Be Able To

Can, could and be able to are used to express a variety of ideas in English:

Ability/Lack of Ability

Present and Future:

can/can’t + base form of the verb

1. Tom can write poetry very well.

2. I can help you with that next week.

3. Lisa can’t speak French.

am / is / are / will be + able to + base form of the verb

am not/ isn’t / aren’t/ won’t be + able to + base form of the verb

1. Mike is able to solve complicated math equations

2. The support team will be able to help you in about ten minutes.

3. I won’t be able to visit you next summer.

Past:

could / couldn’t + base form of the verb

1. When I was a child I could climb trees.

was / were + able to + base form of the verb

wasn’t / weren’t + able to + base form of the verb

hasn’t / haven’t + been able to + base form of the verb

1. I wasn’t able to visit her in the hospital.

2. He hasn’t been able to get in touch with the client yet.

Note: Can and could do not take an infinitive (to verb) and do not take the future auxiliary will.

· Incorrect: I can to help you this afternoon.

· Correct: I can help you this afternoon.

· Correct: I will (I’ll) be able to help you this afternoon.

Possibility / Impossibility

can / can’t + base form of the verb

1. You can catch that train at 10:43.

2. He can’t see you right now. He’s in surgery.

could + base form of the verb

1. I could fly via Amsterdam if I leave the day before.

Ask Permission / Give Permission

Can + Subject + base form of the verb (informal)

1. Can you lend me ten dollars?

Can + base form of the verb (informal)

1. You can borrow my car.

Could + subject + base form of the verb (polite)

1. Could I have your number?

2. Could I talk to your supervisor please?

Make a suggestion – To make a suggestion use:

Could + base form of the verb (informal)

You could take the tour of the castle tomorrow.

May, Might

Formal Permission / Formal Prohibition

may / may not + base form of the verb

1. You may start your exam now.

2. You may not wear sandals to work.

Polite Request

May + subject + base form of the verb

1. May I help you?

Possibility / Negative Possibility

may/ might + base form of the verb

1. We may go out dinner tonight. Do you want to join us?

2. Our company might get the order if the client agrees to the price.

may not / might not + base form of the verb

1. Adam and Sue may not buy that house. It’s very expensive.

2. They might not buy a house at all.

To Make a Suggestion (when there is no better alternative)

may as well / might as well + base form of the verb

1. You may as well come inside. John will be home soon.

2. We might as well take Friday off. There’s no work to be done anyway.

Polite Suggestion

might + base form of the verb

1. You might like to try the salmon fillet. It’s our special today.

Shall, Should, Ought to

To Offer of Assistance or Polite Suggestion (When you are quite sure of a positive answer)

Shall + subject + base form of the verb

1. Shall we go for a walk?

Note: Shall is only used with I or we. It is used instead of will only in formal English.

To Offer of Assistance or Polite Suggestion (When you are not sure of a positive answer)

Should + subject + base form of the verb

1. Should I call a doctor?

A Prediction or Expectation that Something Will Happen

should/shouldn’t + base form of the verb

1. The proposal should be finished on time.

2. I shouldn’t be late. The train usually arrives on time.

To Give Advice

should / ought to + base form of the verb

1. You should check that document before you send it out.

2. You ought to have your car serviced before the winter.

To Give Advice (about something you think wrong or unacceptable)

shouldn’t + base form of the verb

1. James shouldn’t teach him words like those.

Must, Have to, Need to, Don’t have to, Needn’t

Necessity or Requirement

Present and Future:

must / have to / need to + base form of the verb

1. You must have a passport to cross the border.

2. Elisabeth has to apply for her visa by March 10th.

3. I need to drop by his room to pick up a book.

Past:

had to / needed to + base form of the verb

1. I had to work late last night.

2. I needed to drink a few cups of coffee in order to stay awake.

Note: have to and need to are often used in the same context, but many times, need to is used to express something that is less urgent, something in which you have a choice.

Almost 100% Certain

must + base form of the verb

1. Thomas has lived in Paris for years. His French must be very good.

To Persuade

must / have to + base form of the verb

1. You must try this wine. It’s excellent.

2. You have to visit us while you’re in town.

Prohibited or Forbidden

must not / mustn’t + base form of the verb

1. You must not drive over the speed limit.

2. You mustn’t leave medicines where children can get to them.

Lack of Necessity