"Do you mix the salt and the pepper?"

Translation: Unisci il sale e il pepe?

[JonnyRuzzo]

Why is it wrong to add "tu" before the verb here?

[Karmaria]

Wondering this as well

[xyphax]

I don't know if it's necessarily wrong to add the subject pronoun tu, but I think duolingo is trying to teach us to omit them when they're not necessary. This site shows 3 rules when the subject pronoun is actually required:
http://www.italianlanguageguide.com/grammar/pronouns/

[GuerraAmanda]

I'm guessing that if you put the word "tu" after "unisci" it could be right...

[Voltaic117]

Is there any reason why "ed" should not be accepted here? I'm still not 100% clear on when to use it, but "ed il pepe" seemed as good of a place as any.

[Emrani]

It's accepted now. I just used it.

[DigKat]

I said: voi unite il sale e il pepe. Is this wrong? why?

[chaffinches]

Why doesn't 'sale' take the 'lo' form of 'the' here?

[ragnar82]

I believe the rule is that s words take lo if a consonant follows the s (lo squalo, but il serpente).

[xyphax]

sale always has the definite article il

http://www.bbc.co.uk/languages/italian/language_notes/il.html