Let's say someone said, "You must be an idiot" to me to mean that I'm most likely an idiot. As a response to that, can I say these sentences below interchangeably to mean that that person is actually most likely an idiot himself?

  • "No, you must."

  • "No, you must be."

I think the the latter is correct, but the first one somewhat sounds wrong to me.


In conversation, you can omit the verb, or verb phrase, after "must" when replying to a statement containing "must". This applies whether the modal verb 'must' is being used to express necessity...

You must work harder - No, you must [work harder].
You must leave now - No, you must [leave now].
We must run faster - No, you must [run faster].

...or when it is being used to express probability, or an opinion:

You must be an idiot - No, you must [be an idiot].

  • Thank you. Does "No, you must be" sound bad to you? – Fire and Ice Jan 1 '19 at 15:27
  • It sounds like normal conversation. You must or you must be, both equally OK. – Michael Harvey Jan 1 '19 at 15:33
  • I actually have some other questions on this subject, but I'm going to open another topic for it. – Fire and Ice Jan 1 '19 at 17:12

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