Which two statements are true about Oracle network connections?
A) A listener may listen on behalf of only one database instance at a time.
B) A server process checks a user\'s authentication credentials and creates a session if the credentials are valid.
C) A connection request from a client is always first received by a listener running on the port that is used for the connection request for the database server.
D) The listener always spawns a new server process to deal with each new connection.
E) The listener continuously monitors a connection after the user process connects to a service handler.
Answer：BC
(解析：监听可以监听多个实例;如果是共享连接，则不会总是派生出server进程对应一个新的连接;一个连接建立后，就不需要监听再进行监视了，比如可以把监听停止，但是不会影响当前的连接;来自客户机的连接请求总是首先由运行在用于数据库服务器连接请求的端口上的侦听器接收。来自3组：1015267481)