在JQuery中隐藏和显示li

I am having the Html as

我正在使用Html

 <ul>
    <li id="listSize" style="display: block;">
     <label class="topspace">Field Size:</label>

     <select id="fieldSize" name="fieldSize" >
                            <option >Choose a size </option>
                            <option value="small">Small</option>
                            <option value="medium">Medium</option>
                            <option value="large">Large</option>
    </select> 
</li>
    <li id="listPhoneFormat" class="right half" style="display: none;">
    <label class="topspace">Phone Format</label>
    <select id="fieldSize" name="fieldSize">
    <option selected="selected" value="phone" id="fieldPhoneAmerican">### - ### - ####</option>
    <option value="europhone" id="fieldPhoneEuro">International</option>
    </select>
</li>
    <li id="listOptions" style="display: none;">
           <label class="topspace">Options:</label>
           <input id='required' name="required" type='checkbox'>Required</input>
    </li>
<li id="listInstructions" style="display: none;">
    <label class="topspace">Instructions for User </label>
    <textarea cols="40" id="instructions" name="instructions" rows="20" style="width: 98%; height: 70px;"></textarea>

</li>
 <ul>