How to deal with a professor that continuously dismisses student questions?
It may be time to become more assertive in this person's class.


If he immediately answers with, just a minute, we're going to cover that, then you can speak up 5 minutes before class ends, or at the beginning of the following class, for example: "Excuse me, Prof. So-and-So, you mentioned you were going to be covering Topic B.  Since we didn't get to that today/last time, could you please start with that leftover question from last time?
If he immediately answers with, that's what we just covered, follow up immediately, for example, "Could you please clarify how the material you just covered answers my specific question? ... I'm sorry, sir, I don't see how that was relevant to my question." 
If he spends a couple sentences briefly explaining why your question doesn't apply / doesn't work, then you can try something like this: "You feel I asked a stupid question.  Nevertheless, I asked because I would honestly like an answer.  Can you help me formulate the question in an acceptable format?" 


Meeting one on one with certain professors sometimes gets one nowhere, unfortunately.  Still, you could try visiting office hours to find out more about what he's like.