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问题 解答题

小兰6分钟走了390米，照这样的速度，她从家到学校走了18分钟，她家到学校有多少米？

答案

390÷6×18

=65×18，

=1170（米）．

答：她家到学校有1170米．

单项选择题

在Access中，参照完整性规则不包括

A．更新规则

B．查询规则

C．删除规则

D．插入规则
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单项选择题

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.

（5）是（）

A.call

B.state

C.cost

D.error
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