function show (id) {
  if (before_id == '[object HTMLDListElement]' || before_id == '[object]') {
    before_id = new String('object01');
  }
  if (before_id != 'object' + id) {
    document.getElementById('object' + id).style.display = "block";
    document.getElementById(before_id).style.display = "none";
    before_id = new String('object' + id);
  }
  return false;
}