[HttpPost]
    public ActionResult BaiTestIQ(int id)
    {
        var cauhoi = from q in data.Questions
                     join a in data.Answers on q.MaTests equals "IQ"
                     where q.MaCHoi == a.MaCHoi && a.keys == id
                     select new baitest()
                     {
                         Cauhoi = q.Noidung,
                         DAn1 = a.DAn1,
                         DAn2 = a.DAn2,
                         DAn3 = a.DAn3,
                         DAn4 = a.DAn4,
                         DAn5 = a.DAn5,
                         DAn6 = a.DAn6,
                     };
        return PartialView(cauhoi);
    }

<script>
    function loadcauhoi(num) {
        $.ajax({
            dataType: "Html",
            type: "POST",
            url: '@Url.Action("BaiTestIQ","TestIQ")',
            data: { id: num },
            success: function (a) {
                // Replace the div's content with the page method's return.
                alert("success");
                $('#baitetstiq').html(a);
            },
            error: function (jqXHR, textStatus, errorThrown) {
                alert(errorThrown)}
        });
    }
 </script>

<div class="col-md-9" style="border-top-style:double;
border-top-color:aquamarine;
border-top-width:5px; margin-left:-15px">
<p style="text-align:center">
    <b>Thời Gian Còn Lại Là:xxx</b>
</p>
<div id="baitestiq"></div>
@foreach(var item in Model)
{
    <div class="baitest">
        <div class="ques">
            <img src="~/Hinh_Cauhoi/@item.Cauhoi" />
        </div>
        <div class="anw">
            <div class="dapan">
                <img src="~/Hinh_Cauhoi/@item.DAn1" />
            </div>
            <div class="dapan">
                <img src="~/Hinh_Cauhoi/@item.DAn2" />
            </div>
            <div class="dapan">
                <img src="~/Hinh_Cauhoi/@item.DAn3" />
            </div>
            <div class="dapan">
                <img src="~/Hinh_Cauhoi/@item.DAn4" />
            </div>
            <div class="dapan">
                <img src="~/Hinh_Cauhoi/@item.DAn5" />
            </div>
            <div class="dapan">
                <img src="~/Hinh_Cauhoi/@item.DAn6" />
            </div>
        </div>
        <div class="numbertest">
            <ul>
                <li>
                    <a href="javascript:;" onclick="loadcauhoi(2)">1</a>
                </li>