/// <summary>
/// 获取习题有效时间
/// </summary>
/// <param name="vguid"></param>
/// <returns></returns>
public string GetExerciseEffectiveTime(string vguid)
{
var model = _dl.GetExerciseEffectiveTime(vguid);
string effectTime = model.EffectiveDate.ToString("yyyy-MM-dd HH:mm");
return(effectTime);
}