Combobox incompleto, me faltan funciones

[axpicasso]

function cambiar(combo)
{
var index = combo.selectedIndex;
var capa = document.getElementById("pepe");

capa.style.display = (index == 0) ? "none" : "";

if (index == 0)
{
capa.innerHTML = "";
return;
}
else
{
index--;
}

var aDatos =
[
[ "42 a 105 CV" , "105 a 150 CV" , "150 a 300 CV" , "300 a 465 CV" ],
[ "33 a 67 CV" , "67 a 112 CV" , "112 a 180 CV" , "180 a 300 CV" ],
[ "82" , "82 a 130 CV" , "130 a 225 CV" ]
];


var opciones = "<option value=''>Seleccione</option>";

for (i = 0; i < aDatos[index].length; i++)
{
var result = aDatos[index][i];
opciones += "<option value='" + result + "'>" + result + "</option>";
}
capa.innerHTML = "<select name='select2'>" + opciones + "</select>";
}