Form: can + bare infinitive

Can is a modal verb. It is the same for all persons, and is always followed by the bare infinitive (no "to").

FormExample
Positive: subject + can + verbI can speak French. · She can drive.
Negative: subject + can't + verbHe can't swim. · They can't come tonight.
Question: Can + subject + verb?Can you play the piano? · Can she help?
Short answers:Yes, I can. · No, I can't.
can't = cannot "Can't" is the contraction of "cannot" (one word). Both are correct: "I cannot swim" = "I can't swim". In speech and informal writing, use can't.

Three main uses

UseKey ideaExamples
Ability something you know how to do (skill) I can cook Italian food. · She can't read music.
Permission asking or giving permission (informal) Can I use your phone? · You can leave early today. · You can't park here.
Requests asking someone to do something Can you open the door? · Can you speak more slowly, please?
Could = more polite: "Could you help me?" is more polite than "Can you help me?" Both are correct. Use "could" in formal situations or when being extra polite.

Exercises

Choose the correct option.

1. My little sister ___ tie her shoelaces. She's only two.

2. "___ I sit here?" "Of course you can!"

3. ___ you speak any other languages apart from English?

4. You ___ use your phone during the exam. It's not allowed.

5. ___ you turn down the music? I'm trying to sleep.