How do we criticize someone for what they have not done in the past? Is the structure "should have" appropriate for this?

Context: Suppose a 15 years old kid who has lenient parents has got severe eye problems because of playing too much video games. Are the following sentences grammatical and appropriate to tell to their parents?

  1. You should/must have turned the TV off whenever your kid played for more than one hour.
  2. You should/must have curbed the screen time of your kid.
  3. You should/must have been more strict and less lenient parents.

Any other suggestion in addition to the structure "should/must have" ?

  • 2
    The only useful "suggestion" here is "Use should have, not must". For all practical purposes, learners should assume they can only use must in past tense contexts where it means "could not have been different", not to mean "should have acted differently". So must doesn't work in your examples as "belated advice". You can only use it in things like It must have hurt when he punched you or You must have known that (it's not possible that it didn't hurt, or that you didn't know). Commented Feb 4, 2023 at 13:03
  • 1
    Note the guidance in the tag that you chose: "Please explain which sentence you prefer and why." Commented Feb 4, 2023 at 13:26
  • 1
    Should have or ought to have, not must have. Commented Feb 4, 2023 at 13:50

1 Answer 1


"Should have" can be used for giving advice relating to a past event.

These sentences would work if speaking to people whose children are now grown up. You could not use them to give advice to someone whose children are having too much screen time now.

On the other hand, "must have" is used to state assumptions about the past.

It is very warm in the house, John must have left the heating on.

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