function select(label,gifname,leftIndex) {
  var bigPictTag = document.getElementById('pic_mid');
  bigPictTag.style.backgroundImage = "url('" + gifname + "')";
  var pictLabelTag = document.getElementById('pic_label');
  pictLabelTag.childNodes[0].childNodes[0].nodeValue = label;
  var leftContentTag;
  for (var i = 1; i < 9; i++) {
    leftContentTag = document.getElementById('pic_desc' + i);
    leftContentTag.style.display = 'none';
  }
  leftContentTag = document.getElementById('pic_desc' + leftIndex);
  leftContentTag.style.display = 'block';
}