ASP.NET MVC 下拉框传值方式

public ActionResult Index()
{
dk.bll.edu.EduBll<dk.model.edu.SetupRecord> setUpBll = new dk.bll.edu.EduBll<dk.model.edu.SetupRecord>();
List<dk.model.edu.SetupRecord> list = _setUpBll.GetMany(c => c.KeId == _upId && c.MenuCode == "jpjiaxiao").ToList();
var t = new SelectList(list.Select(m => m.s2));
ViewBag.schoolname = t;
return View();
}

<div id="cmg-dialog">
<div class="toolbar">
<a id="icon-cmgsave">保存</a><a id="icon-cmgclose">关闭</a>
</div>
<form class="d-dopen" id="addfrm">
<p>
<span>名称：</span>
@Html.DropDownList("schoolname", ViewBag.schoolname as IEnumerable<SelectListItem>, "请选择", new { @id = "cmg-campus" })
</p>
<p class="hidden">
<span>版本号：</span>
<input id="cmg-dnum" class="cmg-dinput" type="text" name="s2">
</p>
<p class="hidden">
<span>是否有效：</span>
<select id="cmg-deffect" class="cmg-dselect" type="text" name="s3">
<option value="">请选择</option>
<option>有效</option>
<option>无效</option>
</select>
</p>
<p>
<span></span>
<input type="checkbox" name="s4">
<input type="hidden" name="id"/>
</p>
</form>
</div>