Buy some beers for tonight.

Question

Why is it Comprad cervezas para esta noche and not Comprad unas cervezas para esta noche?

Answer

Hola Catriona! Both answers in Spanish are correct, that is to say, you can use the indefinite article or omit it. Without the article, it is more general, and with the article is a bit more specific (some, a few...). The reason why we translated it as "buy some beers for tonight" in English is because in this language it would sound a bit odd to say "buy beers", but in Spanish both options are acceptable. Thanks for your contribution! Silvia.

Answer

Thanks for that explanation, but if both are correct, why is one of them marked wrong?  Just a fine point in English: we would say "Buy some beer for tonight," and either "I had a lot of beer last night" or "I had four bottles of beer," but not "I had a lot of beers."