问题
单项选择题
[听力原文] ？？对不起，老板，我得马上回家一趟，刚才幼儿园的老师打电话来说孩子生病了，发高烧，需要马上送往医院，现在正等着我拿钱送孩子去医院。 说话人现在可能在哪儿？（）
A．家里
B．幼儿园
C．办公室
D．医院
答案
参考答案：C
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[听力原文] ？？对不起，老板，我得马上回家一趟，刚才幼儿园的老师打电话来说孩子生病了，发高烧，需要马上送往医院，现在正等着我拿钱送孩子去医院。 说话人现在可能在哪儿？（）
A．家里
B．幼儿园
C．办公室
D．医院
参考答案：C
| A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication; TCP uses port (71) to accomplish this. Another responsibility of a transport layer protocol is to create a (72) and error-control mechanism at the transport level. TCP uses a sliding (73) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (74) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (75) 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. |
A．ports
B．streams
C．packets
D．cells