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问题 多项选择题

宏小区的传播模型有下述哪几个（）

A.Okumura-Hata模型

B.COST-231-Hata模型

C.COST-231-Walfish-Ikegami模型

D.双射线模型

答案

参考答案：A, B, C

单项选择题

运用假设开发法估价必须考虑资金的( )。

A．实用价值

B．有效价值

C．折算价值

D．时间价值
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单项选择题 共用题干题

A transport layer protocol has several responsibilities, One is to create a process-to-process (program-to-program) communication; TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocol is to create a  (2) and error-control mechanism at the transport level. TCP uses a sliding (3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve  (4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends  (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

空白（4）处应选择（）

A.packet

B.time

C.error

D.phase
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