Modal Verbs

Usually when we want to show our attitude to the situation, we use the verbs for modality. They can express the premission, advice, probability etc.

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').

Let's look through some categories of modal verbs.

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.

Ability

We use 'can' and 'could' to talk about a skill or ability. For example: She can speak six languages.

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. 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.