为什么以下代码会抛出此错误?
"运营商' + ='不能应用于类型'对象'和 '事件处理'"
ComboBox cmbx = new ComboBox();
cmbx.SelectedItem += new EventHandler(cmbx_SelectedItem);
void cmbx_SelectedItem(object sender, EventArgs e)
{
ComboBox cmbbx = sender as ComboBox;
}