辛卯日婚姻:asp的问题，有两个列表框，通过选择班级，另一个列表框中的学生能够随着变动。急!!! 在线等待！

左边列表框：
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<select
onChange="fillSelectFromArray(this.form.SubMenu, ((this.selectedIndex ==-1) ? null : SubMenuinfo[this.selectedIndex-1]));" name="MainMenu" class="menu">
<option value="" selected>具体省级地区
<option value="石家庄市
">石家庄市
</option>
<option value="唐山市">唐山市</option>
<option value="秦皇岛市">秦皇岛市</option>
<option value="邯郸市">邯郸市</option>
<option value="邢台市">邢台市</option>
<option value="保定市">保定市</option>
<option value="张家口市">张家口市</option>
<option value="承德市">承德市</option>
<option value="沧州市">沧州市</option>
<option value="廊坊市">廊坊市</option>
<option value="衡水市">衡水市</option>
</select>

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右边列表框:
<select size=1 name="SubMenu" class="menu">
<option></option>
</select>
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javascript定义
<SCRIPT language=JavaScript>
<!--
SubMenuinfo = new Array(
new Array(
new Array("", ""),
new Array("长安区", "长安区"),
new Array("桥东区", "桥东区"),
new Array("桥西区", "桥西区"),
new Array("新华区", "新华区")
),
new Array(
new Array("", ""),
new Array("路北区", "路北区"),
new Array("滦县", "滦县")

)
...略 定义与左边列表框个数相同的数组.
);

function fillSelectFromArray(selectCtrl, itemArray, goodPrompt, badPrompt, defaultItem) {
var i, j;
var prompt;

for (i = selectCtrl.options.length; i >= 0; i--) {
selectCtrl.options[i] = null;
}
prompt = (itemArray != null) ? goodPrompt : badPrompt;
if (prompt == null) {
j = 0;
} else {
selectCtrl.options[0] = new Option(prompt);
j = 1;
}
if (itemArray != null) {

for (i = 0; i < itemArray.length; i++) {
selectCtrl.options[j] = new Option(itemArray[i][0]);
if (itemArray[i][1] != null) {
selectCtrl.options[j].value = itemArray[i][1];
}
j++;
}

selectCtrl.options[0].selected = true;
}
}
//-->
</SCRIPT>