搜题请搜索小程序“爱下问搜题”
问题 单项选择题

使用引导信号引导接车是指在进站信号机前，LKJ接收到（）信息后，监控列车以不超过20km/h的速度越过该信号机。

A.红黄灯

B.红黄闪灯

C.双黄闪灯

D.黄2闪灯

答案

参考答案：B

计算题

质量均匀分布的球重G=300N，置于竖直墙和支架之间，球半径R=10cm，支架和墙之间的距离a =15cm，各接触处摩擦均不计。（1）试画出球的受力图；（2）求支架和墙对球的作用力。
查看答案
单项选择题

A transport layer protocol usually has several responsibilties. One is to create a process-to-process communication UDP uses （1）numbers to accomplish this. Another responsibility is to provide control mechanisms at the transport level UDP does this task at a very minimal level. There is no flow control mechanism and there is no （2）for received packet. UDP, however, does provide error control to some extent. If UDP detects 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 send streams of data to the transport layer. It is the responsibility of the transport layer at（4）station to make the connection with the receiver chop the stream into transportable units, number them, and send them one by one. it is the responsibility of the transport layer at the receiving end to wait until all the different units belonging to the same process have arrived, check and pass those that are （5） free, and deliver them to the receiving process as a stream.

（3）是（）

A.jobs

B.processes

C.programs

D.users
查看答案