What I believe is we could use "must be verbing" “be” in three ways.

You must be lying (As in you are currently lying)
You must be watching TV (as in future)
You must be regretting (as in you should regret)

Are my interpretations correct?

1 Answer 1


No. All three refer to the ongoing present, and all three have the sense of "I deduce that you are lying/watching tv/regretting".

For example, you might say in a telephone conversation:

I can hear the theme tune to your favourite TV show in the background. You must be watching TV.

The speaker deduces that the person is watching TV from hearing the music.

In none of the sentences does "must" mean an obligation or rule. If you say "You must watch TV" this is a rule.

  • as you said these sentences are refering to "ongoing present" but could you pls tell me if this "present" is referring to the present continuous meaning as in "your are watching TV" or It is a present of " You must have been watching a TV " or It could be both? Apr 10, 2022 at 1:08
  • 1
    It is the present continuous expressed as "be verb-ing", with a modal "must".
    – James K
    Apr 11, 2022 at 20:37
  • James you said earlier that "must be verbing" cannot be an obligation but here, in this thread ell.stackexchange.com/questions/313272/…. I came across that in this sentence "He must be doing his homework when i get home" "must be doing" is used as obligation because "when i get home" is used as time specifier as in future. Though i guess one should not use "must" with any conditional sentence" what do you reckon pls share? Apr 14, 2022 at 1:18

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