获取地区三级下拉菜单其中的一个值

string  sProv = Request.Form["selProv"];
string  sCity = Request.Form["selCity"];

string  sTown = Request.Form["selTown"];

string  areaNum = String.IsNullOrEmpty(sTown) ? (String.IsNullOrEmpty(sCity) ? sProv : sCity) : sTown;