设有关系R（教师编号，姓名，教研室，主任，课程名，学时数）下图是关系R的一个实例。
(1)写出R的主键；(2)分析R中存在的问题。
参考答案：
在我们的生活中，会有很多的因素对我们造成影响，那么影响生物生存的生物因素是指[ ]
A．所有的环境因素
B．环境中影响生物生活的因素
C．影响某种生物生活的其他生物
D．影响某种生物生活的一切因素
In the following essay, each blank has four choices. Choose the most suitable one from the four choices and write down in the answer sheet. Heterogeneous network environments consist of computer systems from (66) vendors that run (67) operating systems and communication protocols. An organization that (68) its computer resources is usually (69) the task of integrating its heterogeneous systems. Typically, each deparlment or division has defined its own network needs (70) OS, LAN topology, communication protocols, applications, and other components.
A．faced on
B．faced with
C．faced about
D．faced up to
(1)写出R的主键；(2)分析R中存在的问题。
(1)写出R的主键；(2)分析R中存在的问题。