function showsub_a(id){
	for (i = 0;i<5;i++){
		document.getElementById("tab_a"+i).className = "menu_bj_02";
		document.getElementById("sub_a"+i).style.display = "none";
	}
		document.getElementById("tab_a"+id).className = "menu_bj_01";
		document.getElementById("sub_a"+id).style.display = "";
}