Modal Verbs: Can, Could, Should, Must, Have to, Need to, May, Might

MODAL VERBS

1. CAN

Expresses ability or capacity to do something (know), possibility (can), and is also used to ask for permission or favors (can).

2. COULD

Expresses the same as can but in the past, although it is more suitable for asking for favors.

3. SHOULD

Used to give or ask for advice and to say what should or should not be done.

4. MUST

In affirmative, expresses obligation and the need or convenience of doing something (must). In negative, expresses prohibition or that something cannot be done because it is not correct to do it.

5. HAVE TO

(Have to) expresses the same as must, the difference is that it is conjugated, that's why it is used in tenses that must does not have.

6. NEED TO

Means the same as have to and since it can be conjugated, it is used in all verb tenses.

7. NEEDN'T

Used to indicate that there is no obligation or need to do something, its use is more formal.

8. MAY

(May, might) expresses possibility in affirmative and negative. In interrogative, it is used to ask for permission or request.

9. MIGHT

(Might) expresses the same as may but here the possibility is more remote.

0. ZERO

IF + PRESENT SIMPLE + PRESENT SIMPLE

Used to express general situations that repeat whenever a certain condition is met. When can be used instead of if.

1. FIRST

IF + PRESENT SIMPLE + WILL

Used to talk about actions that will happen if the indicated condition is met.

2. SECOND

IF + PAST SIMPLE + WOULD (base verb)

Used to talk about hypothetical actions referred to the present, that is, actions that are unlikely to happen, and also to give advice. If the verb is to be, were is usually used for all persons. Advice > If I were you...

3. THIRD

IF + HAD (past participle) + WOULD (past participle)

Used to talk about completely impossible conditions, as they refer to the past and can no longer be fulfilled.