vb.net2010编写的一个简易的加法练习器，由计算机随机产生两个两位正整数的加法练习题，给用户进行加法运行练习，并统计练习结果。-vb.net2010 prepared by the addition of a simple exercise device, two two randomly generated by the computer positive integer addition exercises, an addition to the user running exerci