设计一个加法速度测试程序，程序启动后显示出如图所示的运行界面。用户单击“开始”按钮后开始计时，并分别在文本框1、2中随机生成并显示加数和被加数，用户在文本框3中输入答案，按回车键后程序在答案的后面指示对错，并显示出下一道题。一分钟以后程序统计出出题数量和作对的数量。用户单击“结束”按钮退出程序。(An addition speed test program is designed. After the program is started, the running interface is shown as shown in the diagram. Users click the "start" button to start timing, and respectively in the text box 1, 2 random generating and displaying the addend and summand, users in the text box to enter the answer 3, press enter after the program instructions in the answer behind the right and wrong, and show the next problem. A minute later, the program counts the number of questions and the number of pairs. The user clicks the "end" button to exit the program.)