"Who sells it?" is correct (always capitalize the first letter of a sentence).
Yes, "He sells cars" is correct.
Honda Motors sells cars. correct with a period at the end :)
From 8:00 a.m. until 6:00 p.m., Mr. Downs sells hardware.
"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.
From 8:00 a.m. until 6:00 p.m., Mr. Downs sells hardware. add a colon between 6 and 00
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'.
"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."