Which two statements are true regarding listeners? (Choose two.)
A.Listeners use only the TCP/IP protocol.
B.Multiple listener processes can run simultaneously on a host.
C.Multiple database instances can be registered with a single listener.
D.The listener-related errors can be traced only at the administrative level.
E.Only one database instance can be registered with a single listener at any time.
A 错误，还有 IPC
B 正确，可以设置不同的端口号，从而启动多个监听
C 正确，多个数据库可以注册到同一个监听。
D 错误，相关信息会写入到 Listener Log File
E 和 C 冲突，错误