Starting college can be challenging enough without having to worry about getting on your professor's bad side. Savvy college students soon figure out that there are just certain things never to ask.

As a former Assistant Professor at the US Air Force Academy, in Colorado Springs, CO, I know those little pet peeves that drive professors right up the wall. Unfortunately, professors don't come with an instruction book, so I wrote "College Success Your Way, What Your Professors Won't Tell You and Your Friends Don't Know," so all students can know up front the inside secrets about succeeding in college.

Here are three "killer questions" never to ask your professor. Think twice before you ask them. Although your heart is in the right place, your frustrated professor could hear a completely different message.

"When is it due?"

"Is this testable?"

"I was gone last class. Did I miss anything important?"

Let's take a closer look at why you'll want to avoid these questions.

"When's it due?" You may simply be thinking ahead. But, the professor wonders why you're asking something in your syllabus. Asking your teacher when something is due is like asking where your notebook is. It's your job to know.

"Is this testable?" This seems like a smart question, doesn't it? Nope. It drives professors crazy. Why? Here's what the professor hears when you ask that question: "Do I need to listen now, or can I zone out again, since I'm bored beyond belief, and I'm only taking this class because there was no way out of it?"

While it may be the case that you are barely able to remain conscious as the professor drones on, remember, diplomacy is key. And, it's your job to figure out what might be tested by paying close enough attention so you can tell when points are being repeated and emphasized. Your professor isn't generally going to be so blunt as to say, "And this is on the test." If she does, consider it a gift.

And finally, do not ask, "I was gone last class. Did I miss anything important?" This is actually a common question that, on the surface, seems harmless enough. Aren't you even quite responsible to follow up and ask to make sure you aren't missing out on some crucial point in your education because you didn't attend the last class?

Sadly, dear student, in spite of your best intentions about making up for lost time in following up on any goodies missed, here's what the professor hears, "Did you say anything I'll be tested on?" or worse, "You don't usually say anything important, was last Tuesday an exception?"

Unfortunately, either way, you don't end up looking very good. And oh, by the way, you already missed class, so what's up with that?

Knowing what your drives your professors crazy can help you avoid awkward moments, and let you make your time in college smooth sailing.