"When is dinner?"
Translation:Wanneer is het avondeten?
why you need to define the article ? To have the article the question should be: when is the dinner?
You can't always translate sentences word-for-word, and this is one of those sentences. In Dutch, you need the article and in English, you don't.
Is there a guideline or a resource we could use to find common examples of when we must speak about an object as a definite?