Learn Dutch: Geloven jullie de smoes niet? - Do you not believe the excuse?

This sentence is a direct yes/no question (a main clause). In main clauses, when you negate the entire action and have a specific, definite object like de smoes (the excuse), niet is placed after that object. As you go through this lesson, keep this in mind to see how the placement of niet differs in subordinate clauses!

Could I put niet right after the subject: Geloven jullie niet de smoes?

Not for a standard question. If you put niet right in front of a definite object like de smoes, it creates a strong contrast. It would sound like you are asking: 'Do you believe not the excuse (but rather the truth)?' To simply ask if they don't believe it, niet must go at the end.

Is een smoes the same kind of excuse as an apology?

No. Een smoes (or the commonly used diminutive een smoesje) specifically means a made-up reason, a pretext, or a lie used to get out of trouble. If you want to refer to a genuine apology, you would use een excuus or een verontschuldiging.

Why isn't there a word for 'Do' in the Dutch sentence?

English uses helper verbs like 'do' or 'does' to ask questions, but Dutch does not. Instead, you just invert the word order by putting the verb first. 'You believe' (jullie geloven) simply becomes 'Believe you?' (Geloven jullie?).