function changelocation(id)
{
	document.form1.citys.length =1;
	var id=id;
	var j=0;
	document.form1.citys.options[0] = new Option('全部',"");
	for (j;j < citynum; j++)
	{
		if (allcity[j][0] == id)
		{
			document.form1.citys.options[document.form1.citys.length] = new Option(allcity[j][2], allcity[j][1]);
		}
	}
}