A time-traveller and his student.. A college professor at a small college had just invented time-travel. He knew he couldn't trust just anyone with this secret, so he chose to tell only his best student; an african-american student named Mark. When the professor told him, Mark was shocked! ""So what do you plan to do with you time-machine?"" Mark asked. ""I'm going to kill Hitler when he was a child"" The professor responded. Mark was both appalled and intrigued, so he asked the professor if he …