function chg(id_num){    
         var oa = document.getElementById(id_num);    
         var ob = document.getElementById("test_a");   
		 var ob1 = document.getElementById("test_a1");   
         if(oa.style.display == "block"){    
                 oa.style.display = "none";    
                 ob.innerHTML = "产品高级搜索";  
				 ob1.innerHTML = "产品高级搜索";   
         }else{    
                 oa.style.display = "block";    
                 ob.innerHTML = "关闭产品高级搜索";    
				 ob1.innerHTML = "关闭产品高级搜索";   
         }    
         return false;    
}