慢性肺脓肿最常见的并发症是
A.脓胸B.心包炎C.脑脓肿D.支气管扩张E.大咯血
参考答案:D
设有关系模式R(课程,教师,学生,成绩,时间,教室),其中函数依赖集F如下:
F=课程→→教师, (学生, 课程)→成绩, (时间, 教室)→课程,
(时间, 教师)→教室, (时间, 学生)→教室
关系模式R的一个主键是 (66) ,R规范化程度最高达到 (67) 。若将关系模式R分解为3个关系模式R1(课程,教师)、R2(学生,课程,成绩)、R3(学生,时间,教室,课程),其中R2的规范化程度最高达到 (68) 。
67()
A.1NF
B.2NF
C.3NF
D.BCNF
Questions 16 to 20 are based on the following talk.
A. They get sudden attacks of sleep any time any place. B. They are mostly students enrolled in 8 A.M. classes. C. They are not easily cured if narcolepsy is diagnosed. D. They often sit at a table and their faces fall into a soup.