int r3加入量 = 0, r4更新量 = 0;
            foreach (var item in Students)
            {
                Student r2= dc.Student.SingleOrDefault(o => o.bbid == item.bbid);
                if (r2!=null)
                {
                    r2 = item;
                    r4更新量++;
                }
                else
                {
                    r2 = item;
                    dc.Student.InsertOnSubmit(r2);
                    r3加入量++;
                }
            }
            dc.SubmitChanges();
            p1加入量 = r3加入量;
            p2更新量 = r4更新量;

private static void AddRange<TEntity>(ObjectContext context, 
                                                                  IEnumerable<TEntity> entities,
                                                                  out int adding, out int updating)
    where TEntity : class
{
    var table = context.CreateObjectSet<TEntity>();
    adding = 0;
    updating = 0;

    foreach (var entity in entities)
    {
        var key = context.CreateEntityKey(table.Name, entity);
        var original = context.GetObjectByKey(key) as TEntity;

        if (original == null)
        {
            table.AddObject(entity);
            adding++;
        }
        else
        {
            context.ObjectStateManager.GetObjectStateEntry(key).CurrentValues.SetValues(entity);
            updating++;
        }
    }
}