Modals

Modals verbs are a class of auxiliary verbs. Modal verbs are also called modal auxiliaries or simply modals.

Modals express how a verb:  the ability, possibility, necessity or another condition ofthe main verb.
These verbs are used with main verbs to make statements or ask questions.Conjugates haven't modals or time and can not be used without the main verb.

In English, the main verb is always in infinitive without to, except the modal ought.
In a statement, the word order is subject + modal + main verb.

sujeto	modal	verbo principal
They Ellos	can pueden	come. venir.
Mike Mike	should debe	walk. caminar.

In the questions, word order is subject + modal + main verb.

(yes-no questions)
modal	sujeto	verbo principal
Can ¿Pueden	they	come? venir?
Should ¿Debería	Mike Mike	drive? manejar?

Below are the different manner with some examples and applications.

Modal	Example	Uses
Can	They can control their own budgets. We can’t fix it. Can I smoke here? Can you help me?	Ability / Possibility Inability / Impossibility Asking for permission Request
Could	Could I borrow your dictionary? Could you say it again more slowly? We could try to fix it ourselves. I think we could have another Gulf War. He gave up his old job so he could work for us.	Asking for permission. Request Suggestion Future possibility Ability in the past
May	May I have another cup of coffee? China may become a major economic power.	Asking for permission Future possibility
Might	We'd better phone tomorrow, they might be eating their dinner now. They might give us a 10% discount.	Present possibility Future possibility
Must	We must say good-bye now. They mustn’t disrupt the work more than necessary.	Necessity / Obligation Prohibition
Ought to	We ought to employ a professional writer.	Saying what’s right or correct
Should	We should sort out this problem at once. I think we should check everything again. Profits should increase next year.	Saying what’s right or correct Recommending action Uncertain prediction
Will	I can’t see any taxis so I’ll walk. I'll do that for you if you like. I’ll get back to you first thing on Monday. Profits will increase next year.	Instant decisions Offer Promise Certain prediction
Would	Would you mind if I brought a colleague with me? Would you pass the salt please? Would you mind waiting a moment? "Would three o`clock suit you?" - "That’d be fine." Would you like to play golf this Friday? "Would you prefer tea or coffee?" - "I’d like tea please."	Asking for permission Request Request Making arrangements Invitation Preferences

- The modal auxiliary verbs are always followed by the base form.