通过设置para.txt文件，显示孩子用电脑的时间，只有在规定时间内，屏幕才能用，否则屏幕锁定，无法使用。
可以将该程序加入到启动菜单里，登录系统后自动运行。(By setting up the para.txt file, it shows the time for the child to use the computer. Only in the specified time, the screen can be used, otherwise the screen is locked and can't be used.
The program can be added to the Startup menu and automatically run after the system is logged in.)