text: In Lois McMaster Bujold's novel Memory, Miles Vorkosigan says, "I had a professor at the Imperial Service Academy once, who taught the introduction to tactical engineering course. He said he never bothered changing his tests from term to term to prevent cheating, because while the questions were always the same, the answers changed. I thought he was joking."
  
  In the mid-1960s, I was studying astronomy. Much of what I learnt then has been superseded.