Close your books = not accepted.
I think it should be accepted as well. Especially since "kalian" (plural you) is being used in the sentence. It's reasonable to assume that we're talking about more than one book.
It's accepted now.
Shut your books should also be accepted
Why is it nit necessary to use the men- prefix as "menutup" to make it a verb?
When a verb is used in an imperative sentence, the 'me-' prefix is dropped.
Terima kasih banyak
Hi pool guy 777 cc
buku kalian = yʻallʻs books
Buku kalian is plural. Book changes to books but "y'all's" does not exist except in US southern slang. Perhaps you were having a joke.
I think they were indeed having a gag