Modals

Modal verbs are a kind of helping verb. They are used to say how we think or feel about an action. By using modals, we can say what we think is going to happen, how sure we are that it is going to happen, and how we feel about it happening. By looking at the list of modals below, you can see that each one has a slightly different meaning and usage.

• can — able to / giving permission
  cannot — unable to / withholding permission

  “Martin can leave work early today.”
  “That little boy can tie his shoelaces.”
  “People cannot breath underwater.”
  “My parents said I can't go to the movie.”

• could -- past tense of can / expressing possibility

  could not (couldn't) -- past tense of “cannot”

  “He could run very fast when he was young.”
  “By next spring, she could be president.”
  “We couldn't read your note.”

• should -- it's a good idea / it's probable

  should not (shouldn't) -- it's not a good idea

  “You should get a doctor to look at that.”
  “They left on time, so they should be home soon.”
  “You shouldn't go swimming right after you've eaten.”

• will -- possible or probable in future

  will not (won't) -- to refuse / not possible in future

  “I think he will quit, don't you?”
  “She'll call you at six tonight.”
  “The cat won't come down from the tree.”
  “They will not bother you again.”

• would -- conjecture / past tense of “will”

  would not -- negative conjecture

  “If my dog died, I would be very sad.”
  “The mayor said he would visit the school.”
  “I would not be surprised, if they won.”

  In conversation people usually use “won't” and “wouldn't,” not “will not” and “would not.”

• may/might -- to be possible / granting permission

  may not/might not -- possibly not /withholding permission

  “I thought it might snow.”
  “He may/might come to the party.”
  “May I give the dog a biscuit?“
  “That may/might not be the answer.”

• must -- have to / almost certain

  must not -- are not allowed to

  “He must be hungry; he hasn't eaten today!”
  “Everyone must finish the test before leaving.”
  “You must not smoke in the building.”
  “That stair must not have been very strong if it broke.”