Sometimes I have some difficulties in making it clear for my students why sometimes the questions don't have an auxiliary verb. For example, in the sentence: "How many workers work in that factory?", you don't need an auxiliary verb(do) because the question is about the subject of the sentence. But if you ask:" How many workers do you know in that factory?" you need the auxiliary verb because the question word is not referring to the subject of the sentence. Is that right? Could you, please, give me a more technical answer, so I can explain it more clearly to my students?
Thanks for answering
Regards
Manuela Rocha