我想要的是,只有从下拉菜单中选择某个选项才能访问该文本框,并且我有如下的html表单:在多种情况下在下拉菜单中选择一个选项启用文本框
<tr>
<td>a. Did any of your staff participate in training or orientation sessions related to any aspect of social performance management, during the reporting year?
<td >
<select name="mfi_4_a_i">
<option>Please choose one.</option>
<option>Yes</option>
<option>No</option>
<option>No, but planning in future</option>
</select>
<p>if not,and not planning please explain why not?</p>
<input type="text" name="mfi_4_a_ii" class="init" disabled="disabled"/>
</tr>
现在,当在未来选择否,但计划被选中,那么该文本必须是enabled.This下拉菜单的类型以这种形式已经被多次使用,所以我必须启用另一个类似的情况下,文本框所以如何写一个单一的函数来做到这一点。帮我解决问题。