Polite grammar

[Tyrn]

Hi,

Duolingo really stresses conditionals:

¿Nos traería sal y aceite para la ensalada?

although it accepts the present tense, too:

¿Nos trae sal y aceite para la ensalada?

Which way is more natural? I have an impression that Duolingo just sticks to the English grammar whenever possible (Would you bring us salt and oil for the salad?).

As a student, I'm interested in bulletproof polite grammar, because I can't help being imperfect with the subtle things like my intonation, the nature of my collocutor, etc. For instance, I already know that the usted imperative can be a big mistake.

Any ideas about how to be perfectly polite without being a perfect speaker are welcome .

[Rusty]

Using the conditional is certainly a more polite way to express a command, but there is other phrasing that is better received in certain circumstances. I believe this site covers them all.