function plane_search(){
	if(!checkform()){
	   return;
	}
	document.InlandForm.submit();

}
	function checkform(){      
	      if (document.InlandForm.bCity.value==""){
	          alert("请填写出发城市!");
	          document.InlandForm.bCity.focus();
	          return false;
	          }
	
		  if (document.InlandForm.eCity.value==""){
	          alert("请填写目的城市!");
	          document.InlandForm.eCity.focus();
	          return false;
	          }
	          
		  if(getThreeWordByCity(document.InlandForm.bCity.value)==""){
	      	 alert("请填写正确的出发城市!");
	      	 return false;
			}
			else{
			document.InlandForm.BeginCity.value = getThreeWordByCity(document.InlandForm.bCity.value);
			}
			if(getThreeWordByCity(document.InlandForm.eCity.value)==""){
	      	 alert("请填写正确的目的城市!");
	      	 return false;
			}
			else{
			document.InlandForm.EndCity.value = getThreeWordByCity(document.InlandForm.eCity.value);
			}
			if(document.InlandForm.bCity.value==document.InlandForm.eCity.value){
			alert("很抱歉，出发城市与到达城市不能同名，请重新输入。");
			return false;
			}
	      if (document.InlandForm.BeginDate.value==""){
	          alert("请填写出发日期!");
	          document.InlandForm.BeginDate.focus();
	          return false;
	          }
			
			if(!isDateString(document.InlandForm.BeginDate.value))
			{
			  alert("请填写正确的日期格式!");
	          document.InlandForm.BeginDate.focus();
	          return false;
			}
			if(document.InlandForm.LineType(1).checked){
		      if (document.InlandForm.BackDate.value==""){
		          alert("请填写返程日期!");
		          document.InlandForm.BackDate.focus();
		          return false;
		          }
				
				if(!isDateString(document.InlandForm.BackDate.value))
				{
				  alert("请填写正确的日期格式!");
		          document.InlandForm.BackDate.focus();
		          return false;
				}
			}		
			var d = new Date();
			var s = d.getFullYear()+"-"+(d.getMonth()+1)+"-"+d.getDate();
			if(stringToDate(document.InlandForm.BeginDate.value)<stringToDate(s))
			{
			  alert("您输入的日期无效!");
	          document.InlandForm.BeginDate.focus();
	          return false;
			}
	
		 if(document.InlandForm.LineType(1).checked){
		   if (stringToDate(InlandForm.BeginDate.value,true)>stringToDate(document.InlandForm.BackDate.value,true)){
		   alert("返程日期不能早于出发日期！");
	       document.InlandForm.BackDate.focus();
	       return false;
		   }
		  }
		  return true;
	}
	
	function have_img_onclick() {
	  if (document.InlandForm.LineType(0).checked){
	      document.getElementById("xingcheng3").style.display="none";
		  }
	  else if (document.InlandForm.LineType(1).checked){
	      document.getElementById("xingcheng3").style.display="block";
		  }
	}
	
	
	function have_onclick() {
	  document.InlandForm.submit();
	}