如何为我的桌子添加另一个子菜单？

Question

I had a problem. I just downloaded this code from htmldrive.net. I'm using it for my school project and I would like to add another sub menu when the word science is hovered over. Thanks.

HTML/PHP

                <ul id="nav">
                    <li><a href="home.php">Home</a></li>
                    <li><a class="hsubs" href="questions.php">Questions</a>
                        <ul class="subs">
                            <li><a href="">Science</a></li>
                                        <ul class="subss">
                                        <li><a href="">Science</a></li>
                                        </ul>
                            <li><a href="">English</a></li>
                            <li><a href="">Math</a></li>

                        </ul>
                    </li>
                      <li><a class="hsubs" href="facilities1.php">Facilities</a>
                        <ul class="subs">
                            <li><a href="#">Submenu 2-1</a></li>
                            <li><a href="#">Submenu 2-2</a></li>
                            <li><a href="#">Submenu 2-3</a></li>
                            <li><a href="#">Submenu 2-4</a></li>
                            <li><a href="#">Submenu 2-5</a></li>
                            <li><a href="#">Submenu 2-6</a></li>
                            <li><a href="#">Submenu 2-7</a></li>
                            <li><a href="#">Submenu 2-8</a></li>
                        </ul>
                    </li>
                    <li><a class="hsubs" href="#">Events</a>
                        <ul class="subs">
                            <li><a href="#">Submenu 3-1</a></li>
                            <li><a href="#">Submenu 3-2</a></li>
                            <li><a href="#">Submenu 3-3</a></li>
                            <li><a href="#">Submenu 3-4</a></li>
                            <li><a href="#">Submenu 3-5</a></li>
                        </ul>
                    </li>
                    <li><a href="#">About Us</a></li>

                    <li><a href="#">            
    <?php
    $member=$_SESSION['member'];
    $result=mysql_query("select * from account where member='$member'")or die(mysql_error);
    $row=mysql_fetch_array($result);
    $FirstName=$row['name'];
    $Age=$row['surname'];
    echo " Welcome ".$FirstName;
    ?>
    </a></li>
                    <li><a href="logout.php?id=$member \">Logout</a></li>
                    <div id="lavalamp"></div>
                </ul>

CSS

    #nav,#nav ul {
        list-style: none outside none;
        margin: 0px 0px 0px 0px;
        padding: 0;
    }
    #nav {
        background: url('aa.jpg') no-repeat scroll 0 0 transparent;
        clear: both;
        font-size: 12px;
        height: 58px;
        padding: 0 0 0 9px;
        position: relative;
        width: 1200px;
    }
    #nav ul {
        background-color: #222;
        border:1px solid #222;
        border-radius: 0 5px 5px 5px;
        border-width: 0 1px 1px;
        box-shadow: 0 5px 5px rgba(0, 0, 0, 0.5);
        left: -9999px;
        overflow: hidden;
        position: absolute;
        top: -9999px;
        z-index: 2;

        -moz-transform: scaleY(0);
        -ms-transform: scaleY(0);
        -o-transform: scaleY(0);
        -webkit-transform: scaleY(0);
        transform: scaleY(0);

        -moz-transform-origin: 0 0;
        -ms-transform-origin: 0 0;
        -o-transform-origin: 0 0;
        -webkit-transform-origin: 0 0;
        transform-origin: 0 0;

        -moz-transition: -moz-transform 0.1s linear;
        -ms-transition: -ms-transform 0.1s linear;
        -o-transition: -o-transform 0.1s linear;
        -webkit-transition: -webkit-transform 0.1s linear;
        transition: transform 0.1s linear;
    }
    #nav li {
        background: url('menu_line.png') no-repeat scroll right 5px transparent;
        float: left;
        position: relative;
    }
    #nav li a {
        color: #FFFFFF;
        display: block;
        float: left;
        font-weight: normal;
        height: 30px;
        padding: 23px 20px 0;
        position: relative;
        text-decoration: none;
        text-shadow: 1px 1px 1px #000000;
    }
    #nav li:hover > a {
        color: #00B4FF;
    }
    #nav li:hover, #nav a:focus, #nav a:hover, #nav a:active {
        background: none repeat scroll 0 0 #121212;
        outline: 0 none;
    }
    #nav li:hover ul.subs {
        left: 0;
        top: 53px;
        width: 180px;

        -moz-transform: scaleY(1);
        -ms-transform: scaleY(1);
        -o-transform: scaleY(1);
        -webkit-transform: scaleY(1);
        transform: scaleY(1);
    }
    #nav ul li {
        background: none;
        width: 100%;
    }
    #nav ul li a {
        float: none;
    }
    #nav ul li:hover > a {
        background-color: #121212;
        color: #00B4FF;
    }

    #lavalamp {
        background: url('lavalamp.png') no-repeat scroll 0 0 transparent;
        height: 16px;
        left: 13px;
        position: absolute;
        top: 0px;
        width: 64px;

        -moz-transition: all 300ms ease;
        -ms-transition: all 300ms ease;
        -o-transition: all 300ms ease;
        -webkit-transition: all 300ms ease;
        transition: all 300ms ease;
    }
    #lavalamp:hover {
        -moz-transition-duration: 3000s;
        -ms-transition-duration: 3000s;
        -o-transition-duration: 3000s;
        -webkit-transition-duration: 3000s;
        transition-duration: 3000s;
    }
    #nav li:nth-child(1):hover ~ #lavalamp {
        left: 13px;
    }
    #nav li:nth-child(2):hover ~ #lavalamp {
        left: 88px;
    }
    #nav li:nth-child(3):hover ~ #lavalamp {
        left: 170px;
    }
    #nav li:nth-child(4):hover ~ #lavalamp {
        left: 250px;
    }
    #nav li:nth-child(5):hover ~ #lavalamp {
        left: 335px;
    }
    #nav li:nth-child(6):hover ~ #lavalamp {
        left: 445px;
    }
    #nav li:nth-child(7):hover ~ #lavalamp {
        left: 550px;
    }
    #nav li:nth-child(8):hover ~ #lavalamp {`enter code here`
        left: 565px;
    }

Answer 1

I this FIDDLE what you're looking for?

I've shortened your HTML a bit - you can expand it just following the same patterns.

HTML

<nav>
<ul>
   <li><a href="#">Home</a></li>
   <li><a href='#'>Questions</a>
      <ul>
        <li><a href="#">Science</a>
           <ul>
              <li><a href="">Physics</a></li>
              <li><a href="">Chemistry</a></li>
              <li><a href="">Physiology</a></li>
           </ul>
           </li>
        <li><a href="">English</a></li>
        <li><a href="">Math</a></li>
      </ul>
      </li>
    <li><a href="#">Facilities</a>
           <ul>
              <li><a href="#">Submenu 2-1</a></li>
           </ul>
           </li>
</ul>
<nav>

The CSS is in the fiddle, so I won't have to post it here -quite long.

One teaching point is that you really can do most dropdowns with pure CSS - don't need classes, ID's etc.