Must, may, might, can't

Grammar: must, may, might, can't (deduction)

• When you are sure something is true: must

           They must be out. There aren't any lights on.
           She must have a lot fo money. She drives a Porsche.

• When you think something is possibility true: may/might 

          His phone's off. He might be on the plane now.
          She's not at home. She may be working.

• When your are sure something is impossible/not true: can't 

          He can't be sick. I saw him at the gym.
          They can't be Italian. They're speaking to each other in Spanish.

must, may, might, can't