在缓冲区中预放了一些字母,运行时,可按照屏幕上显示的字母进行输入练习,每输入完一行按回车键后,可显示出练习输入的时间（可以用系统时间计时）-Pre-amplifier in the buffer zone in a number of letters, run-time can be displayed on the screen in accordance with the input letters to practice, each finished entering his press Enter, you can show that the importation of practice time (system time can be a time)