have seen The sentence is absolutely correct. Sorry Joan, sorry Julia, study more.

Right on, Eliot. Nothing wrong with "many a boy and many a girl". It is just a more "poetic" way to say "many boys and many girls". You would normally use the singular verb with "many a ... " -- singular pronouns go with the construction also, as in this example: ~"Many a man has lost his life at sea." This construction has been described as "notionally plural" but singular in usage. But since there are two of these at play here, the verb is plural: ~"Many a boy and many a girl have seen it since then." If we separate the boys from the girls, it is singular: ~"Many a boy has seen it since then." ~"Many a girl has seen it since then."

I think even the question not right. Should be: Many girls and many boys___it since then. the answer is: A have seen

agree with Joan.

I agree with Joan.