RULES
1. We use can to talk about the present || past and could to talk about the past II present .
2. We use a base form without || with to after can and could.
3. The he / she / it form of can is can || cans.
4. The negative forms are can’t and couldn’t || don’t can and didn’t can.
5. We don’t use || use do and did to make questions with can and could. For example:
At what age can most people talk?
When could you first speak English?