can / can't

Rules

• Rule 1: can never changes

  can is the same for everyone: I can, he can, she can, they can. There is no “cans”!

  Pattern: Subject + can + verb

  Example: My sister can skate.

  Example: A monkey can climb trees.

• Rule 2: can + base verb

  After can, use the base verb: no -s, no -ing, no to.

  Pattern: can + verb (no ~~to~~, ~~-s~~, ~~-ing~~)

  Example: He can whistle.

  Example: Dolphins can jump out of the water.

• Rule 3: Negative → can't

  Use can't (cannot) for things we are not able to do.

  Pattern: Subject + can't + verb

  Example: I can't whistle.

  Example: Snakes can't walk.

• Rule 4: Questions, short answers, permission

  Put can first to ask: Can you…? Short answers: Yes, I can. / No, I can't. Use Can I…? to ask politely for permission.

  Pattern: Can + subject + verb …?

  Example: Can you play chess? — Yes, I can.

  Example: Can I borrow your eraser, please?

Common mistakes

• She cans swim. → She can swim.

  can never takes -s.

• I can to read. → I can read.

  No to after can.

• He can plays tennis. → He can play tennis.

  Use the base verb.