What is Modals of Deduction? Modals of Deduction Examples and Exercises

What is Modals of Deduction? Modals of Deduction Examples and Exercises



What are Modals? 

Modals are found in the auxiliary verbs class when viewed grammatically. These are auxiliary verbs such as can, may, could, may… We use modals to make predictions/inferences based on a situation with evidence and support. The reason why these verbs are more than one is that it changes according to how sure we are about the prediction made and whether it is positive or negative.


MUST: We use it in sentences that we are sure of the correctness or almost certain of the accuracy.

  •      She has a lot of expensive cars, she must have some Money.
  •      He isn’t answering the phone, she must be busy.
  •      He must be around here because his the blue car is parked there now.
  •      This bus must be a good model because it’s too expensive.
  •      I am sure he must be 23 because he looks so young.
  •      You must be patient until you get what you want from life.
  •      You must get some sleep because you worked hard.
  •      That big blue car must be mine.


CAN’T: We use it in sentences where we are sure or almost certain of something impossible to happen.

  •      They can’t be Turkish, they’re speaking Portuguese.
  •      My wallet can’t be in my pocket, I already looked there.
  •      This car can’t belong to that guy. He looks so poor.
  •      You can’t be afraid of dogs.
  •      You can’t solve your problems by crying like a baby.
  •      You just drank water, you can’t be thirsty.
  •      She can’t be a mother, too young to be a mother.
  •      He can’t be dead, I just saw him at his big house.


MAY/MIGHT/COULD: We use it in sentences that are not certain, but that we believe to be possible.

  •      He might be in his bedroom, time is too late.
  •      They might be going to Europe. All of them were studying at universities in Europe.
  •      It could have been Jesica on the yellow bus, her the school bus was also this color.
  •      He might be in the Gym, sometimes he goes there.
  •      I might have been here when I was a child but I don’t sure.
  •      You may have heard this music, we heard it in my dad’s car last week.
  •       Selina is very tall so he might be good at basketball. The school girls basketball team was missing.



MAY NOT/ MIGHT NOTE: We use it in sentences that are uncertain that will not happen, but that we believe will not happen.

  • Luis hasn’t called me. He may not havemy number. I should text him my number.


NOTE: We use “may/might/could” when estimating, but we use “can” when deducing. The difference between them should not be forgotten and should be used very carefully.


NOTE: The opposite of “must” is not “mustn’t”. We use “can’t” to indicate the opposite of “must”. You should not make this mistake, which is often made.

– You know the glasses can’t be put there, then my mom gets angry. (TRUE)

– You know the glasses mustn’t be put there, then my mom gets angry. (FALSE)


NOTE: One of the most common mistakes is that “could not” is not used as the opposite of “could”. Although the suffix “not” is used as a contrast for “may and might”, there is no such usage in “could”.

– He could not be sleeping. It’s evening time. (FALSE)

– He can’t be sleeping. It’s evening time. (TRUE)