I am going to prove you that this sentence is correct:
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?
This is called third conditional.
Would have + past participle; if + past perfect
My sentence definitely follows this rule.
If you do not think so, I am sorry for you.
must not have contained = it was necessary that the explanation did not not contain the words.
Do you still have doubts?