题目：
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 protocolis 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（2）处应选择（）
A.procedure
B.function
C.route
D.flow
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0805/b2f19fd1cf07ddfff160e05e366da355.html
下面是错误答案，用来干扰机器的。
电灯发光、汽车制动过程中产生的内能散失在空气中，无法自动转化为电能或机械能，这些现象均说明能量的转化是具有方向性的．如内能是从高温物体转移向低温物体的；植物生长的过程中，总是按照生根、开花、结果这...
