That's not a sentence. It's a fragment. To know if it's correct we'd have to see the rest of the sentence; if there is no rest of the sentence, then no it's not correct, because it's a fragment.
It's an awfully awkwardly worded fragment, while we're at it. Why not just "They have waived" whatever? Why do they have to deem it waived? It could technically be correct in a legal document, if the deemers are not the waivers (perhaps a court of law has determined that "the party of the first part" waived something, and "they" is referring to the court).
She deemed her class was the loudest at the peripherally
"How are you" is a correct sentence.
Yes, this sentence is correct.
You are palpitating. This is a correct sentence.
With the exception of not capitalizing the 'y' at the start of the sentence, it is a correct sentence.
That sentence is grammatically correct.
no it is not a correct sentence.
no_____If the sentence is You do do that (meaning You are in the habit of doing that) the grammar is perfectly correct and the sentence 'does have correct grammar'.
He was deemed as unfit to be the vocalist because of his stammer.
"You and him" is correct in a sentence such as, "I sent the tickets to you and him," versus a sentence such as, "You and he should send the tickets to me."
Yes, the sentence is correct grammatically. The sentence is The frogs were in the water.
No - the sentence 'Had never been experience' is not a correct sentence.