某夜，摸黑下楼梯。我机械地重复着下踏台阶的动作，孰料最后一脚竟被垫了一下，扭伤了脚踝。原来，我已走完了台阶，扭伤了脚踝的这一步正是我踏上平地的第一步。 这听起来似乎不可思议：走在高低错落的楼梯上没有扭伤脚，到了平地上怎么反倒伤了脚？其实，这并不奇怪。试想， One night, dark down the stairs. I mechanically repeated the steps down the stairs, guessed that the last leg was actually pad a bit, sprained ankle. It turned out that I had finished the steps, sprained ankle this step is my first step onto the ground. This sounds incredible: walking in the level of scattered stairs did not sprain feet, to the ground on how to down injured foot? In fact, this is not surprising. Just imagine,