Can and Could

The verbs can and could are followed by the 1st form of the verb. E.g. "I can work weekends." or "I could work 18 hours a day when I was younger." Could is the past of can.

Click here for the forms of can

Here are the forms of could:

Statements: I could. You could. He could. She could. It could. We could. You could. They could.
Examples:
 I could speak. You could use. He could program. She could enter data. It could organize. We could drive. You could read. They could speak.
Negatives: I could not. You could not. He could not. She could not. It could not. We could not. You could not. They could not.
Examples:
 I could not enter data. You could not drive. He could not speak. She could not use. It could not organize. We could not read. You could not organize. They could not drive.
Short forms of negatives: I couldn't. You couldn't. He couldn't. She couldn't. It couldn't. We couldn't. You couldn't. They couldn't.
Examples:
 I couldn't enter data. You couldn't drive. He couldn't speak. She couldn't use. It couldn't organize. We couldn't read. You couldn't organize. They couldn't manage.
Questions: Could I? Could you? Could he? Could she? Could it? Could we? Could you? Could they?
Examples:
 Could I manage? Could you program? Could he drive? Could she speak? Could it correct? Could we enter data? Could you use? Could they answer?
Short positive answers: Yes, I could. Yes, you could. Yes, he could. Yes, she could. Yes, it could. Yes, we could. Yes, you could. Yes, they could.
Short negative answers: No, I couldn't. No, you couldn't. No, he couldn't. No, she couldn't. No, it couldn't. No, we couldn't. No, you couldn't. No, they couldn't.

Use can

  • to say that someone knows how to do something.
    • E.g. "I can speak English, but I can't speak Chinese."
  • to say that it is possible for someone to do something. It is used for the present and the future.
    • E.g. "Tom can usually work weekends, but Jennifer can't."
    • E.g. "Bill can work tomorrow, but he can't work next Sunday."
  • to ask someone to do something.
    • E.g. "Can you tell me the time?"
    • "Could you tell me the time?" is also possible.
  • to ask if it's OK to do something.
    • E.g. "Can I use your computer?"
    • "May I use your computer?" is also said.
  • with the verb "have" to ask for something.
    • E.g. "Can I have a copy of that letter, please?"

Use could

  • to say that someone knew how to do something.
    • E.g. "When Lutz was a child he could speak German, but he couldn't speak English".
  • to say that it was possible for someone to do something.
    • E.g. "I couldn't work last week, but Sarah could."
  • to ask someone to do something.
    • E.g. "Could you help me, please?"
    • "Can you help me, please?" is also possible.