public List <Student> GetNotEnroled(Guid idEnvironment) { List <Student> students = new List <Student>(); var environment = _environmentRepository.GetEnvironmentByIdIncludeDependencys(idEnvironment); environment.Students.ForEach(student => { if (environment.CulturalExchange.FirstOrDefault(culturalExchange => culturalExchange.StudentId == student.Id) == null) { students.Add(student); } }); return(students); }