先接收任一个字符，判断该字符是否为空格键，是空格的话就退出，否则就开始计时。计时时，输入F12时，计时暂停，再按除空格的任意键继续，按空格就退出。-First to receive any one character, to judge whether the characters for the space bar is a space, then on exit, or start running. Time, enter the F12, the time suspended, and then in addition to spaces of any key to continue, according to a space on the exit.