We use can to talk about what is possible, what we are able or free to do: She can drive a car. John can speak Spanish. Normally, we use can for the present. But it is possible to use can when we make present decisions about future ability: Can you help me with my homework? (present) We use could to talk about what was possible in the past, what we were able or free to do: I could swim when I was 5 years old. My grandmother could speak seven languages. We often use could in a question to ask somebody to do something. The use of could in this way is fairly polite (formal): Could you tell me where the bank is, please?