if(document.images) {
 var imgs = new Array();
 imgs[0] = new Image();  imgs[0].src = "image/nurse/misa/1.jpg";
 imgs[1] = new Image();  imgs[1].src = "image/nurse/misa/2.jpg";
 imgs[2] = new Image();  imgs[2].src = "image/nurse/misa/3.jpg";
 imgs[3] = new Image();  imgs[3].src = "image/nurse/misa/4.jpg";
}

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}