เลือก list menu แล้วให้แสดงฟอร์มย่อยขึ้นมาโดยไม่ต้อง Submit ทำอย่างไรค่ะ

<select name="select_year" id="select_year" onchange="window.location='show.php?select_year='+this.value+''">
<option value="1" >1 Phase</option>
<option value="3" >3 Phase</option> 
</select>

<script src="http://code.jquery.com/jquery-latest.js"></script>
 <select id="pagelist">
	  <option value="first_form.php">First</option>
	  <option value="second_form.php">Second</option>
	  <option value="third_form.php">Third</option>
 </select>

  <div id="showSelected" style="border:1px solid blue;display:block;width:250px;height:30px;">
  </div>
  <script language="javascript">
  $("#pagelist").change(function(){
	var url = $("#pagelist option:selected").val();
	$("#showSelected").empty().load(url);	
  });
</script>

<script src="http://code.jquery.com/jquery-latest.js"></script>
 <select id="pagelist">
	  <option value="">กรุณาเลือก</option>
	  <option value="firstOption">First</option>
	  <option value="secondOption">Second</option>
 </select>

  <div id="firstOption" style="display:none">
  <form method="post" action="first.php">
  <h2 style="color:red">First Option</h2>
  1:<input type="text" name="box1" /><br />
  2:<input type="text" name="box2" /><br /> 
  <input type="submit" />
  </form>
  </div>

  <div id="secondOption" style="display:none">
  <form method="post" action="second.php">
  <h2 style="color:blue">Second Option</h2>
  1:<input type="text" name="box1" /><br />
  2:<input type="text" name="box2" /><br /> 
  <input type="submit" />
  </form>
  </div>
  <script language="javascript">
  $("#pagelist").change(function(){
	var viewID = $("#pagelist option:selected").val();
	$("#pagelist option").each(function(){
		var hideID = $(this).val();
		$("#"+hideID).hide();
	});
	$("#"+viewID).show();	
  });
</script>

$('#pagelist').change(function(){
   window.open( this.value, '_blank').focus(); 
});

window.open( this.value,  '<?=$_get['pagelistl']?>' ).focus();