jQuery 怎么获取table中某行下拉框中的值

jQuery 如何获取table中某行下拉框中的值
我编写了一个每行都带下拉框和button的table，每行内容由数据库循环输出，如何获取某一行中下拉框选中的值？

				 	<%	 	 

				 	

				 	String res ="select * from item natural join result where item.item_id=result.item_id and user_id ="+sessionname;	


					ResultSet r = statement.executeQuery(res);

				 	

				 		while (r.next()) {

				 			String item = r.getString("name");

				 			int date = r.getInt("date");

				 			int rank =r.getInt("grade");

				 	%>

				 	<tr>

				 		<td><B><%=item %></B></td>

				 		<td align="center"><B><%=date  %></B></td>

				 		<td align="center"><B><%=rank %></B></td>

				 		<td class="result"> 

				 		<select id="grade">

  							<option value ="1">1</option>

  							<option value ="2">2</option>

  							<option value="3">3</option>

  							<option value="4">4</option>

  							<option value="5">5</option>

						</select></td>

				 		<td><B><input type="button" class="btn"  value="提交"/></B></td>

				 	</tr>

------解决思路----------------------

<script src="http://www.w3school.com.cn/jquery/jquery-1.11.1.min.js">

</script>

<table>   <tr>

                         <td><B>11111</B></td>

                         <td align="center"><B>2222</B></td>

                         <td align="center"><B>3333</B></td>

                         <td class="result"> 

                         <select id="grade">

                              <option value ="1">1</option>

                              <option value ="2">2</option>

                              <option value="3">3</option>

                              <option value="4">4</option>

                              <option value="5">5</option>

                        </select></td>

                         <td><B><input type="button" class="btn"  value="提交"/></B></td>

  </tr> <tr>

                         <td><B>11111</B></td>

                         <td align="center"><B>2222</B></td>

                         <td align="center"><B>3333</B></td>

                         <td class="result"> 

                         <select id="grade">

                              <option value ="1">1</option>

                              <option value ="2">2</option>

                              <option value="3">3</option>

                              <option value="4">4</option>

                              <option value="5">5</option>

                        </select></td>

                         <td><B><input type="button" class="btn"  value="提交"/></B></td>

  </tr> <tr>

                         <td><B>11111</B></td>

                         <td align="center"><B>2222</B></td>

                         <td align="center"><B>3333</B></td>

                         <td class="result"> 

                         <select id="grade">

                              <option value ="1">1</option>

                              <option value ="2">2</option>

                              <option value="3">3</option>

                              <option value="4">4</option>

                              <option value="5">5</option>

                        </select></td>

                         <td><B><input type="button" class="btn"  value="提交"/></B></td>

  </tr></table>

<input type="button" value="获取" onclick="alert('第2行select：'+$('table tr:eq(1) select').val())"/>

<script>

  $('.btn').click(function(){alert($(this).parents('tr').find('select').val())})

  </script>