Grammar: Can / Could

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"Can" and "Could" are modal verbs in English grammar used to express ability, possibility, permission, and to make requests or offers. Their usage in the United States follows the general rules applicable in English, but with some nuances specific to American English.


  • Ability: To show what someone can do. Example: "She can drive."
  • Possibility: To indicate something is possible. Example: "It can rain today."
  • Permission/Requests: Informally ask or give permission, or make requests. Example: "Can I use your phone?"


  • Past Ability: Used for abilities in the past. Example: "I could swim when I was younger."
  • Polite Requests: To make requests sound more polite. Example: "Could you help me?"
  • Hypothetical Situations: For things that might happen. Example: "If I had time, I could read more."

In the U.S.:

"Can" is common in both casual and formal speech. "Could" is preferred for politeness or formal situations. Both are widely understood and used, with "can" often for permission in casual settings.