键盘打字练习游戏。本程序实现键盘打字练习功能，用户可续选择练习的难易程度，根据难易程度的不同，字母下落的速度会有所区别，游戏结束之后，程序能够统计用户练习的结果并输出。-Keyboard typing practice game. Keyboard typing practice program to achieve this functionality, users can choose exercises continued ease, according to the different difficulty levels, letters are subject to the whereabouts of the speed difference, the game is over, the program can be a user of statistics practice results and output.