如何在编辑模式MVC 5中将所选项目设置为动态下拉列表

Question

@if (ViewBag.language != null)
{
    foreach (var item in ViewBag.language)
    {
        <div class="control-label col-md-2">Language</div>
        <div class="col-md-6">
            @Html.DropDownList("LanguageId", null, new { @class = "form-control" },@item.LanguageID)
        </div>
    }
}

ViewBag.Langauge包含LangaugeID和foreach次迭代，我想将下拉列表选定值设置为@item.langaugeID的值

ViewBag.LanguageId = new SelectList(db.Languages, "LanguageId", "LanguageName");

包含数据库中的所有语言

for (int i = 0; i < count; i++)
{
    int languageid = StudentLanuguages[i];
    List<tblStudentLanguageMapping> StudentLan = new List<tblStudentLanguageMapping>();
    StudentLan = (from a in db.tblStudentLanguageMappings 
                  where a.StudentLanguageMappingId == languageid
                  select a).ToList();
    std.AddRange(StudentLan);
}
ViewBag.language = std;