取得下拉框的选择数据
var zone=document.getElementById("zoneId");var area=document.getElementById("areaId");var build=document.getElementById("buildId");var unit=document.getElementById("unitId");var zoneName = zone.options[zone.selectedIndex].text;var areaName = area.options[area.selectedIndex].text;var buildName = build.options[build.selectedIndex].text;var unitName = unit.options[unit.selectedIndex].text;??