var query=from c in Slgl_CustomerReception 
          where c.ProjectId==9
          let id=Slgl_FollowUpRecords.Where(r=>r.CustomerId==c.id
                  && r.FollowDate<=Convert.ToDateTime("2011-7-20"))
                 .OrderByDescending(r=>r.id).First().id
          join f in Slgl_FollowUpRecords
          on f.id equals id into g
          from f in g.DefaultIfEmpty()
          select new 
           {
              id=c.id,
              name=c.CustomersName,
              names=f==null?"":f.FollowUpTheWay,
              FollowDate=f==null?DateTime.Now:f.FollowDate,
              fid=f==null?0:f.id
            };