private void button2_Click(object sender, EventArgs e)
{
TaxOperation op = new TaxOperation(new EnterpriseTax());
Form1.ActiveForm.Text = "企业所得税为：" + op.GetTax(60000.00);
}
private void button1_Click(object sender, EventArgs e)
{
TaxOperation op = new TaxOperation(new PersonalTax());
Form1.ActiveForm.Text = "个人所得税为：" + op.GetTax(5000.00);
}