function aa() {
    var temp = document.getElementById("click").innerText;
    if (temp == "隐藏图书") {
	document.getElementById("opener").style.display="none";
	document.getElementById("click").innerText="显示图书";
	}else{
	document.getElementById("opener").style.display="block";
	document.getElementById("click").innerText="隐藏图书";
	}
}