"The English do not eat soup; they drink it."
Translation:Les Anglais ne mangent pas la soupe, ils la boivent.
"De la soupe" would be grammatically wrong here, since it is a negative sentence (basic rule, sometimes it's a bit more complicated than that). You can say, "ils mangent de la soupe" or "ils ne mangent pas de soupe". In the example sentence, though, the emphasis is not on the quantity of soup, but on what the English (supposedly) do with it. Partitive articles (du, de la, de l', des) are used to express a certain quantity of something and generally mean "some".
Actually, what you have written is perfectly acceptable to say in English, it just doesn't mean the same thing as the French sentence you have been given to translate.
Strangely enough, 'The English do not eat some soup; they drink it' would be more true in essence than 'The English do not eat soup, they drink it'.
Speaking as an English person, we eat most types of soup but there are some soups that we drink instead - namely cup a soups.
Les Anglais ne mangent pas de soupe, ils la boivent I thought I read somewhere you don't use an article unless we are using a form of the verb être?
I believe Duo is wrong here. If we say "ils mangent la soupe", it means they eat THE soup. We know what soup we're talking about. But here we're talking about soup in general, and if we say "la soupe", we're talking about all the soup in the world.
But since we're talking about soup in general, it should be "de la soupe", as we're talking about soup, not a specific pot of soup.