那位牛人愿意帮帮忙？？我这个作业明天交，临时学来不及了。。帮忙的万分感谢哈。。。。

开发一个XHTML文档，其中包含了一组文本框和一个提交按钮(1) 文本框的提示内容为苹果(每斤5元)、桔子(每斤3.5元)、香蕉(每斤4元)，文本框是用来接收数值输入，表示购买了几斤此类水果，都应该有自己的onclick事件处理程序，这些事件处理能够将对应的水果价格添加到总价格中。(2) 针对提交按钮的事件处理程序必须能产生一个alert窗口，给用户提示总价格。(3) 对文档中文本框添加真实性检查功能，对文本框输入的检查应该保证在0-99之间。

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">#apDiv1 {
position:absolute;
width:157px;
height:51px;
z-index:1;
left: 476px;
top: 514px;
}
#apDiv2 {
position:absolute;
width:128px;
height:73px;
z-index:2;
left: 404px;
top: 161px;
}
</style>
</head><body>
<script language="javascript" type="text/javascript">

</script>
<h1> 欢迎来到水果店</h1>
<table width="556" border="10">
  <tr>
    <td width="110" height="55">水果类型</td>
    <td width="105">单价（元/斤）</td>
    <td width="144">购买数量（斤）</td>
    <td width="151">小计（元）</td>
  </tr>
  <tr>
    <td height="75">苹果</td>
    <td>5.00</td>
    <td width="144"><form id="form1" name="form1" method="post" action="">
      <label for="txt1"></label>
      <input name="txt11" type="text" id="txt10" size="4" maxlength="4"  />
      </form></td>
    <td><div id="apDiv2"></div></td>
  </tr>
  <tr>
    <td height="113">桔子</td>
    <td>3.50</td>
    <td><form id="form2" name="form2" method="post" action="">
      <label for="txt2"></label>
      <input name="txt22" type="text" id="txt2" size="4" maxlength="4" />
    </form></td>
    <td> </td>
  </tr>
  <tr>
    <td height="117">香蕉</td>
    <td>4.00</td>
    <td><form id="form3" name="form3" method="post" action="">
      <label for="txt3"></label>
      <input name="txt33" type="text" id="txt3" size="4" maxlength="4" />
    </form></td>
    <td> </td>
  </tr>
</table>
<div id="apDiv1">
  <form id="form4" name="form4" method="post" action="">
    <input type="submit" name="final" id="final1" value="确认结账" onclick=" check()" />
  </form>
</div>
<p> </p>
<p>

</p>
</body>
</html>
我是建议文本框离开焦点后自动把当前的价格计算放到右边表格的div中，我看你div都加id了应该是准备这样。其他的参考另外一个帖子吧。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk" />
<title>水果</title>
<style type="text/css">
  #a{
width:600px;
height:300px;
font-size:15px;
color:white;
position:absolute;
top:100px;
left:400px;
background-color:blue;
z-index:3;
}
</style>
<script language="javascript">
document.onreadystatechange = function(){
if(document.readyState=="complete")
{
allElements=document.getElementsByTagName("input");
for (var i = 0; i < allElements.length; i++) {
if (allElements[i].className =="fruit") {
allElements[i].onblur=function(){
count(allElements,this);
//....如果修改数据..用ajax
}
}
}  //end for
} //end if
} function count(els,th){
   var ct=0;
   var this_value=th.value;
   if(isNaN(this_value)){  //只能数字
th.value=0;
return false;
   }
   if(parseFloat(this_value)>99){
th.value=99; //小于99
   }
for (var i = 0; i < els.length; i++) {
ct+=parseFloat((els[i].value)*(els[i].getAttribute("rel")));
}
    document.getElementById("b4").value=ct.toFixed(2);}</script>
</head>
<body background="雪花.gif">
<bgsound loop="-1" src="纯音乐-忧伤还是快乐.mp3" >
<div id="a" >
<br/>
<h3 align="center">水果商店</h3>
<br>
<p align="center">
<form name="form1">
苹果（ 5元\斤 ) <input type="text"  value="0" size="4" class="fruit" rel="5"></form>
<form name="form2">
桔子（3.5元\斤) <input type="text"  value="0" size="4" class="fruit" rel="3.5"></form>
<form name="form3">
香蕉（ 4元\斤 ) <input type="text"  value="0" size="4" class="fruit" rel="4"></form><form name="form3">
日蕉（ 8元\斤 ) <input type="text"  value="0" size="4" class="fruit" rel="8"></form>
<form>
总价格：
  <input typr="text" id="b4" disabled="disabled" value="0" size="25" /></form>
<form>
<button onclick="add(5);">清零</button>
</form>
</p>
</div>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="BuyFruit.aspx.cs" Inherits="MessageSend.BuyFruit" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script src="Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>
<script type="text/javascript" language="javascript">
    function Commit() {
        var AllPay = document.getElementById("txtAllPay").value;
        alert("您需要支付的总金额为：" + AllPay + "元!");
    }    function Apple() {
        var AppleCount = document.getElementById("txtApple").value;
        if (AppleCount >= 0 && AppleCount < 100) {
            var ApplePay = AppleCount * 5;
            return ApplePay;
        }
        else {
            alert("请输入0-99之间的斤数!");
            $("#txtApple").val("");
            return 0;
        }    }    function Banana() {
        var BananaCount = document.getElementById("txtBanana").value;
        if (BananaCount >= 0 && BananaCount < 100) {
            var BananaPay = BananaCount * 4;
            return BananaPay;
        }
        else {
            alert("请输入0-99之间的斤数!");
            $("#txtBanana").val("");
            return 0;
        }
    }    function Orange() {
        var OrangeCount = document.getElementById("txtOrange").value;
        if (OrangeCount >= 0 && OrangeCount < 100) {
            var OrangePay = OrangeCount * 7;
            return OrangePay;
        }
        else {
            alert("请输入0-99之间的斤数!");
            $("#txtOrange").val("");
            return 0;
        }
    }    function Allpay() {
        var apple = Apple();
        var banana = Banana();
        var orange = Orange();
        var Allpay = apple + banana + orange;
        $("#txtAllPay").val(Allpay);
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Label ID="Label1" runat="server" Text="苹果(5元/斤) ,请选择买入"></asp:Label>
        <input id="txtApple" type="text" onkeyup="Allpay()" />
        <asp:Label ID="Label2" runat="server" Text="斤"></asp:Label>
    </div>
    <div>
        <asp:Label ID="Label3" runat="server" Text="香蕉(4元/斤) ,请选择买入"></asp:Label>
        <input id="txtBanana" type="text" onkeyup="Allpay()" />
        <asp:Label ID="Label4" runat="server" Text="斤"></asp:Label>
    </div>
    <div>
        <asp:Label ID="Label5" runat="server" Text="桔子(7元/斤) ,请选择买入"></asp:Label>
        <input id="txtOrange" type="text" onkeyup="Allpay()" />
        <asp:Label ID="Label6" runat="server" Text="斤"></asp:Label>
    </div>
    <br />
    <div>
        <asp:Label ID="Label9" runat="server" Text="总金额:"></asp:Label>
        <input id="txtAllPay" type="text" value="0" />
        <asp:Label ID="Label7" runat="server" Text="元"></asp:Label>
    </div>
    <br />
    <br />
    <div>
        <input id="btnCommit" onclick="Commit()" type="button" value="提交订单" style="width: 100px" />
    </div>
    </form>
</body>
</html>
Banana（）
Orange（）....?如果有一千种水果。那么很可怕啊。
虽然我写的比较粗，不过水果可以无限个.
只需加class="fruit" rel="3.5"
其中rel为价格
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
span{display:inline-block;
     width:100px;
text-align:center;}
#result{color:red;
        font-weight:bold;
margin-top:5px;}
</style><script type="text/javascript">
function init(){
function $(id){return(document.getElementById(id));}
reg = /^[0-9]{1,2}$/;
p = $("p");
a = $("a");
o = $("o");
result = $("result");
p.value ="";
a.value ="";
o.value ="";
result.value = "";
}function cal(event){
if(event == a){
if(!a.value.match(reg)){
alert("苹果的数量输入不符")
return false
}
else{
result.value = Number(result.value) + Number(a.value)*3;
}
}
else if(event == o){
if(!o.value.match(reg)){
alert("橘子的数量输入不符")
return false
}
else{
result.value = Number(result.value) + Number(o.value)*2;
}
}
else if(event == p){
if(!p.value.match(reg)){
alert("雪梨的数量输入不符")
return false
}
else{
result.value = Number(result.value) + Number(p.value)*1;
}
}
}window.onload = init;
</script>
</head><body>
<form>
<fieldset>
<legend>自动算价钱</legend>
<span>
<p>种类</p>
<p>数量（斤）</p>
</span>
<span>
<p>苹果</p>
<input id="a" type="text"  onchange="cal(a)"  style="width:40px; border:1px solid #999;"/>
</span>
<span>
<p>橘子</p>
<input id="o" type="text"  onchange="cal(o)"  style="width:40px; border:1px solid #999;"/>
</span>
<span>
<p>雪梨</p>
<input id="p" type="text"  onchange="cal(p)"  style="width:40px; border:1px solid #999;"/>
</span>
</fieldset>
<div>总价:<input type="text" id="result" style="width:20px"/>元</div>
</form>
</body>
</html>
<head>
<script language="javascript">
function cost()
{
var cc=sum();
alert("Your total cost is $ "+cc);
}
function sum()
{
    var a,b,c,total;
var dom=document.getElementById("aa");
if(dom.elements[0].checked)
a=1;
else a=0;
if(dom.elements[1].checked)
b=1;
else b=0;
    if(dom.elements[2].checked)
c=1;
else c=0;
total=(0.590*a+0.490*b+0.390*c)*(1.00+0.050);
return total;
}
</script>
</head><body>
<h4>fruit order form</h4>
<form id="aa" action="">
  <p>
    <input type="checkbox" onclick="sum()"/>
    apple
    <br/>
    <input type="checkbox" onclick="sum()"/>
   orange
    <br />
    <input type="checkbox" onclick="sum()"/>
   banana<br />
   <input type="button"  value="提交" onclick="cost()"/>
  </p>
</form>