问题：缺少')'

里面有双引号，需要转下：
document.writeln(" <td align=center><input type=\"Button\" value=\"提交\" onClick=\"javascript:window.location.href='http://localhost/shop/shopsearch.aspx?ProductName='+form3.ProductName.value+'&ClassID='+form3.classid.options[form3.classid.selectedIndex].value+'&BrandName='+form3.brandname.options[form3.brandname.selectedIndex].text;\" /></td>");