知识运用:(下图中好像多了个'(' ) 实现代码: 1 2 3 4 5 6 7 8 9 10 11 12 privatevoidbutton1_Click(objectsender, EventArgs e) { if(validate(textBox1.Text)) textBox1.BackColor = Color.Green; else textBox1.BackColor = Color.Red; } publicboolvalidate(stringstr_email) { returnSystem....