Using "must".

Can we use "must not have (done) below? If not, what are the alternatives?

"What would you have said verbals are if you had been allowed to say only one sentence and this sentence must not have contained the words: participle, gerund, infinitive?"

Thanks in advance

What would you say verbals are if you can say only one sentence, which cannot contain the words: participle, gerund, infinitive.

Correction:

What would you say verbals are if you could say only one sentence, which cannot contain the words: participle, gerund, infinitive.

Yes, I know there are alternatives, but can one use "must not have" there? That's my question.

No, you can't, Tommie. "must have+Participle II" is used as a guess, eg
She must have forgotten about the date.
In prohibitions we only use "must not+Infinitive". I suppose your question is connected with the sequence of tenses, but it doesn't work with MUST.

Brennus

< 'must not have contained' which is grammatically correct but which sounds wordy and awkward in most cases.>

Most replies have stated that it is grammatically incorrect. Why do you say it is correct?

I mustn't have parsed it correctly.

Even simpler:

"What would you have said verbals are if you had been allowed to say only one sentence, not using the words participle, gerund, infinitive?"

Tommie, I don't see anything ungrammatical about the original sentence. It's just a bit unwieldy.

<I mustn't have parsed it correctly.>

Indeed not. The one you've just offered is present deduction and not at all the same as that "must not have contained" (obligation) in the original post.

Even even simpler:

What would you say verbals are? The sentence, must not use the words participle, gerund, or infinitive?