I would be both naïve and lying if I said I believed everyone does all the work for class and always pays attention. Sometimes you might not have time, or you may be having a bad day or you just may not care. Whatever, I don’t care, that’s your choice. But you should at least have the intelligence to hide the fact that you aren’t paying attention or doing the work.
What you should not do is ask three questions in a row that have already been answered in class. The professor might give you the benefit of the doubt (your fellow students won’t) after the first question, but by the time you have made him repeat everything he’s already said, he’s going to notice. You could instead try asking someone else after class, although if you continually do this — like certain people in my classes — I’m going to be forced to question your intelligence, or at least your work ethic.
Same thing goes for doing the reading. I would highly recommend at least opening the reading or glancing at it. But if that’s too much to ask, then just don’t comment on it. Nothing shows that you didn’t do the reading like asking a question that was answered in the very first sentence of the paper.
And if you happen to be a person who does both of these things on a regular basis, I would like to politely suggest either finding some other class to take, or to stop talking in class. Because the people who frequently demonstrate that they haven’t prepared and aren’t even paying attention just look stupid and annoying to everyone else.