Modals with multiple uses

Modal Verbs

Click here for all the exercises about modal verbs

Here's a list of the modal verbs in English:

can	could	may	might	will
would	must	shall	should	ought to

Modals are different from normal verbs:

1: They don't use an 's' for the third person singular.
2: They make questions by inversion ('she can go' becomes 'can she go?').
3: They are followed directly by the infinitive of another verb (without 'to').

Probability:

First, they can be used when we want to say how sure we are that something happened / is happening / will happen. We often call these 'modals of deduction' or 'speculation' or 'certainty' or 'probability'.

For example:

• It's snowing, so it must be very cold outside.
• I don't know where John is. He could have missed the train.
• This bill can't be right. £200 for two cups of coffee!

Ability

We use 'can' and 'could' to talk about a skill or ability.

For example:

• She can speak six languages.
• My grandfather could play golf very well.
• I can't drive.

Obligation and Advice

We can use verbs such as 'must' or 'should' to say when something is necessary or unnecessary, or to give advice.

For example:

• Children must do their homework.
• We have to wear a uniform at work.
• You should stop smoking.

Permission

We can use verbs such as 'can', 'could' and 'may' to ask for and give permission. We also use modal verbs to say something is not allowed.

For example:

• Could I leave early today, please?
• You may not use the car tonight.
• Can we swim in the lake?

Habits

We can use 'will' and 'would' to talk about habits or things we usually do, or did in the past. 

For example:

• When I lived in Italy, we would often eat in the restaurant next to my flat.
• John will always be late!

Exercise 1: Modals of Possibility and Probability for Past Situations 
Exercise 2: Could haveshould have would have

Past modals and phrasal modals of obligation

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.

• 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. 

Firm obligation, etc. - must and have to 

The verb must only exists in the simple present and present perfect forms. 
While the present form can express obligation, necessity, certainty or strong probability, thepresent perfect forms only express a strongly felt opinion or supposition.

All persons	Present	Present perfect
Affirmative	must	must have
Negative	must not, mustn't	must not have, mustn't have

If other tenses are required, the speaker or writer must use forms of the synonymous modal verb "have to" .  This modal auxiliary has all normal tenses, including progressive or continuous forms; these are not common, but need to be used in some cases.

Principal tenses	Present	Present perfect	Past	Future
Affirmative:	has to, have to	has had to have had to	had to	will have to
Negative;	does not have to, do not have to , doesn't have to don't have to	has not had to have not had to	did not have to didn't have to *	will not have to won't have to

Exercise 1: Choose the best phrase to complete the sentences 
Exercise 2:  Modals of Obligation