top_img = new Array()
top_img[0] = ["img/photo01_l.jpg","Photo1"];
top_img[1] = ["img/photo02_l.jpg","Photo2"];
top_img[2] = ["img/photo03_l.jpg","Photo3"];
top_img[3] = ["img/photo04_l.jpg","Photo4"];
top_img[4] = ["img/photo05_l.jpg","Photo5"];

function chengeImg(i){
	document.topimg.src = top_img[i][0];
	document.topimg.alt = top_img[i][1];
}