function tab_change(ts) {
	var liArray = document.getElementById("word_tab").getElementsByTagName("li"); 
	for (i=0; i< liArray.length; i++){
		liArray[i].className = "tab_visible";
		if(liArray[i] == ts) {
			document.getElementById("tab"+i).style.display = "";
		}else{
			document.getElementById("tab"+i).style.display = "none";
		}
	}
	ts.className = "tab_current";
}