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问题 单项选择题

关于臀位，正确的是()

A．胎体纵轴与母体纵轴垂直

B．完全臀位，指胎儿双髋关节屈曲，双膝关节伸直

C．胎心在母体脐下方听得最清楚

D．妊娠34周之前不必纠正胎位

E．胎儿脐部晚出后，胎头娩出时间最长不能超过8分钟

答案

参考答案：E

选择题

下列实验操作不正确的是(      )

A．用酒精灯加热试管里的固体时先预热

B．在稀释浓硫酸时，将水沿器壁慢慢注入浓硫酸里，并用玻璃棒搅拌

C．气体发生装置在盛装药品前需检验装置的气密性

D．称量氢氧化钠固体时用小烧杯盛装
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单项选择题

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

TCP uses a sliding （） protocol

A．path

B． window

C． frame

D．diagram
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