Modal can in questions

Can is used to express ability or to say that something is possible. Can is the same for all subjects. We don't add an 'S' in the third person like other verbs.

To form the negative we add " not " after can to form one word: cannot. Not necessarily saying YOU can't run naked in the middle of the street but in general it is not possible for anyone. We use could to:. We use could to talk about what was possible in the past, what we were able or free to do:.

We use I positive and couldn't negative for general ability in the past. But when we talk about one special occasion in the past, we use be able to positive and couldn't negative. Look at these examples:. We often use could in a question to ask somebody to do something. The use of could in this way is fairly polite formal :. Although we look at be able to here, it is not a modal verb. It is simply the verb be plus an adjective able followed by the infinitive.

We look at be able to here because we sometimes use it instead of can and could. We use be able to to express ability. If we say "I am able to swim", it is like saying "I can swim". We sometimes use be able to instead of "can" or "could" for ability.

For example,. For example:. Alan can swims well. Alan can to swim well. Alan can swimming well. Alan could swam well. Can she play guitar? Could you speak English when you were a child?

Are you able to understand the homework? Were you able to finish the test? Was he able to pass the exam? The verbs may, might and could show possibility now and in the future. In this case, they have the same meaning.

B: Really? It might snow?! If the temperature is high, it may not snow. It may rain. B: Well, I guess I could still go for a walk in the rain. Compare these sentences.