我有一个存储库类和一个服务类，如下所示:publicclassDinnerRepository{DinnerDataContextdb=newDinnerDataContext();publicDinnerGetDinner(intid){returndb.Dinners.SingleOrDefault(d=>d.DinnerID==id);}//OthersCode}publicclassService{DinnerRepositoryrepo=newDinnerRepository();Dinnerdinner=repo.GetDinner(5);//OtherCode}这会引发错