<input name=button1 type=button value="按" onclick="this.style.display='none';document.getElementById('button2').style.display=''">
<input name=button2 style="display:none" type=button value="按2">
<input name=button2 style="display:none" type=button value="按2">
<input id="button2" name=button2 disabled type=button value="按2">