怎么把两个集合的结果进行合并？

public IList<BRShow> GetBulInfo()

        {

//查询出所有的内容 （）

            var result = from a in ((Entities)this.DataContext).SPEPBULLETIN

                         join b in ((Entities)this.DataContext).USERS on a.USERID.ToUpper() equals b.ACCOUNT.ToUpper()



                         orderby a.POSTDATE descending

                         select new BRShow { ID = a.ID, TITLE = a.TITLE, NAME = b.NAME, POST_LEVEL = a.POST_LEVEL, POSTCONTENT = a.POSTCONTENT, POSTDATE = a.POSTDATE, bulletinread = 0 };

//在result上查询所有为1的   

            var result2 = (from r in result 

                          join b in ((Entities)this.DataContext).BULLETIN_RECORDS

                          on r.ID equals b.ID

                          select r).ToList();

            foreach (var r in result2) { r.bulletinread = 1; };

            return result2; 

        }