store_exec[2] = new Array(['1', 'Chri'], ['2', 'ju']);

function populate_exec(formul, firBox, secBox, secVal) {
  var box = formul.elements[firBox];
  var box2 = formul.elements[secBox];
  var number = box.options[box.selectedIndex].value;
  if (!number) return;
  var list = store_exec[number];
  box2.options.length = 0;
  for(i=0;i<list.length;i++) {
    box2.options[i] = new Option(list[i][1],list[i][0]);
    if(i == secVal) { box2.options[i].selected = true; }
  }
}