"Could you pass me the salt, please?"

Translation: Îmi dai sarea, te rog?

[HaimRosenstein]

what is wrong with :
Puteți să mi- dați sarea, vă rog.
as in plural, or in a polite way to ask?

[PhilipNikolayev]

Puteți să îmi dați sarea.

[MozJames]

Why would I not be able to say "tu îmi dai sarea, te rog?"

[Richard951146]

I really wish to have an audio for this example to get to know the emphasis of the voice while asking a favour.

[orourke.joe]

I used vă rog instead of te rog and it was marked incorrect. Up until this point we have been using the two interchangeably.

[Veronica474574]

Not completely interchangeable as te rog is singular, va rog is plural

If you put "dai" in the first part than you are imply speaking to you singular & thus must follow the rule throughout the sentence. So "Îmi dai sarea, te rog?"
I presume you could have "Îmi dati sarea, va rog?" as an alternative as that would follow the rule of a plural you being spoken to.

I am still learning too so this is what I understand of it :)