Deduction About the Present — Must/Might/Can’t Be

The lights are off and no one answers the door. What do you think happened?

Notice

  • She must be out. (I am almost certain)
  • He might be asleep. (it’s possible)
  • They can’t be home. (I am almost certain it’s not true)

Rule

We use must for a confident guess about the present (almost certainly true), might/could/may for a possible guess (maybe true), and can’t for a confident negative guess (almost certainly not true). This is different from must = obligation — here it means logical deduction.

Practice

  1. The car is gone — she ___ (must) have left already.
    Answer: must
  2. He isn’t answering — he ___ (might) be busy.
    Answer: might
  3. She ___ (can’t) be tired, she just woke up.
    Answer: can’t
  4. The lights are on — someone ___ be home.
    Answer: must
  5. It ___ (could) rain later, the sky is grey.
    Answer: could

Connect

Practise choosing must/might/can’t for present deductions.

Try Grammar Quiz →

CEFR: Spoken Interaction — deal with everyday situations by reasoning aloud about likely explanations.

Azizul Hakim
Latest posts by Azizul Hakim (see all)
PreviousNext