物业服务企业确需改变公共建筑和共用设施用途的时候必须由（）来依法办理有关行政审批手续。

A.业主大会

B.业主委员长

C.业主委员会

D.业主大会 * * 团

A transport layer protocol usually has several responsibilities. One is to create a process-to-processcommunication UDP uses（1）numbers to accomplish this. Another responsibility is to provide controlmechanisms at the transport level, UDP does this task at a very minimal level. There is no flow control mechanismand there is no（2）for received packet. UDP, however, does provide error control to some extent. If UDPdetects an error in the received packet, it will silently drop it.

The transport layer also provides a connection mechanism for the processes. The （3）must be able to sendstreams of data to the transport layer. It is the responsibility of the transport layer at （4） station to make theconnection with the receiver chop the stream into transportable units, number them, and send them one by one. Itis the responsibility of the transport layer at the receiving end to wait until all the different units belonging to thesame process have arrived, check and pass those that are （5）free, and deliver them to the receiving process asa stream.

（2）是（）

A.connection

B.window

C.ackmowledgement

D.destination