我正在尝试为visual Studio中的下拉列表创建If语句。当在列表中选择一个值时，我希望它在被选择后自己显示出来，尽管列表中的所有值都被输出。下面是我正在使用的代码：

protected void btnCalculate_Click(object sender, EventArgs e)
        {
            //Declare Variables 
            String strFrance;
            String strPortugal;
            String strItaly;
            String strSpain;
            String strAmsterdam;
            String strPoland;

            //Assign Values 
            strFrance = "300";
            strPortugal = "350";
            strItaly = "400";
            strSpain = "400";
            strAmsterdam = "250";
            strPoland = "350";

            if (lstPackages.SelectedItem.Text == "France") ;
            {
                Response.Write("The Price of France is" + strFrance + "<br />");
            }

            if (lstPackages.SelectedItem.Text == "Portugal") ;
            {
                Response.Write("The Price of Portugal is" + strPortugal + "<br />");
            }

            if (lstPackages.SelectedItem.Text == "Italy") ;
            {
                Response.Write("The Price of Italy is" + strItaly + "<br />");
            }
            if (lstPackages.SelectedItem.Text == "Spain") ;
            {
                Response.Write("The Price of Spain is" + strSpain + "<br />");
            }
            if (lstPackages.SelectedItem.Text == "Amsterdam") ;
            {
                Response.Write("The Price of Amsterdam is" + strAmsterdam + "<br />");
            }
            if (lstPackages.SelectedItem.Text == "Poland") ;
            {
                Response.Write("The Price of Poland is" + strPoland + "<br />");
            }