<html>
<head>
<script>
function verif(){
s=document.getElementById('pais');
t=document.getElementById('otro');
if(s.value=="Otro"){
t.disabled=false;
document.getElementById('otropais').style.display= "";
s.disabled=true;
}
}
function re(){
document.getElementById('pais').disabled=false;
document.getElementById('pais').selectedIndex=0;
document.getElementById('otro').disabled=true;
document.getElementById('otropais').style.display= "none";
}
</script></head>
<body>
<form><table><tr><td><select name="pais" id="pais" size="1" tabindex="4" onchange="verif()">
<option value=""><--Elegir un país--></option>
<option value="Alemania">Alemania</option>
<option value="Antillas Holandesas">Antillas Holandesas</option>
<option value="Argentina">Argentina</option>
<option value="Otro">Otro</option>
</select><input name="" type="button" value="Recomenzar" onClick="re();">
</td>
</tr>
<tr style="display: none;" id="otropais">
<td align="right" style="font-size: 10pt">Escribe el país:</td>
<td><input type="text" name="pais" id="otro" size="30" maxlength="30" disabled></td>
</tr>
</table>
<input type="submit" name="Submit" value="Enviar">
</form>
</body>
</html>