public questionandanswer Add4(int id, questionandanswer question)
        {
            // 向试题表里增加试题
            question = db.questionandanswer.Add(question);
            include_question_between_bank_and_questionandanswer tmp = new include_question_between_bank_and_questionandanswer
            {
                BankID     = id,
                QuestionID = question.ID
            };

            // 向题库里增加试题
            db.include_question_between_bank_and_questionandanswer.Add(tmp);
            db.SaveChanges();
            return(question);
        }
        public bool Update4(int id, questionandanswer question)
        {
            questionandanswer tmp = db.questionandanswer.Where(p => p.ID == id).FirstOrDefault();

            if (tmp != null)
            {
                // 修改
                tmp.Content = question.Content;
                tmp.Answer  = question.Answer;
                tmp.Score   = question.Score;
                db.SaveChanges();
                return(true);
            }
            else
            {
                return(false);
            }
        }