select แล้วโชว์ textและselect และselectแล้วค่อยโชว์อีกตามลำดับ

  <script language='javascript'>
  function enable_other(){
     var sel = document.getElementById('sel_work').options[document.getElementById('sel_work').selectedIndex].value;
     if(sel == 1){
       document.getElementById('one').style.display="inline"; 
       document.getElementById('two').style.display="none";
       document.getElementById('three').style.display="none";
     }else if(sel == 2){
       document.getElementById('two').style.display="inline";
      document.getElementById('one').style.display="none"; 
      document.getElementById('three').style.display="none";
     }else if(sel == 3){
       document.getElementById('three').style.display="inline";
      document.getElementById('one').style.display="none"; 
      document.getElementById('two').style.display="none";
     }
	}
</script>


<select id='sel_work' name='sel_work' onchange='enable_other();'>
  <option value='1'>1</option>
  <option value='2'>2</option>
  <option value='3'>3</option>
</select>

<div id='one' style='display:none;'>
     <input type='text' name='txtother' id='txtother' value=''  >
</div>
<div id='two' style='display:none;'>
<select id='work' name='work'>
  <option value='1'>one</option>
  <option value='2'>two</option>
  <option value='3'>three</option>
</select>
</div>
<div id='three' style='display:none;'>
<input name="sex" type="radio" id="sex"  value="0" />
		  YES
</div>