This document discusses modals of deduction in English, including might/may, can't, must, and can't vs must. It explains that might/may indicate something is possibly true, can't shows something is impossible/not true, and must means something is sure to be true. It provides examples for each modal. The document also notes that could is used instead of might/may in positive sentences, and that be + gerund is often used after modals of deduction to indicate an action.

1. MODALS OF DEDUCTION
(Present)
EF Intermediate 6B

3. Might/May
• Something is possibly true
Tony’s phone is switched off. He might/may be
on the play now, or just boarding
Laura might/may not like that skirt. It’s not
really her style
I don’t know where Kate it. She may/might be at
work or at the gym

4. Might/May
• DO NOT use can instead of may/might
Tony’s phone is switched off. He can be on the
plane now, or just boarding.
• You can use could instead of may/might in
positive sentences
Tony’s phone is switched off. He could be on the
plane now, or just boarding.

5. CAN’T
• Sure something is impossible/not true
Nigel can’t earn much money in his job. He’s still
living with his parents
That woman can’t be Jack’s wife. Jack’s wife has
dark hair

6. MUST
• Sure something is true
The neighbours must be out. There aren’t any
lights on in the house
Your sister must have a lot of money if she drives
a Porsche

7. CAN’T vs MUST
• MUST and CAN’T (not MUSTN’T) are opposites
in this context
The neighbours must be out. There aren’t any
lights on in the house
The neighbours can’t be out. All the lights are on
in the house
NOT: the neighbours mustn’t be out.

8. Be + gerund
• Be + gerund is often used after modals of
deduction
They might/may be preparing a party. I saw them
buying drinks in the supermarket this morning
They must be having a party. The music is very loud
They can’t be having a party. I can’t hear any music