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问题 单项选择题

罐式加油车加油时，从开始加油至（）后，立即从过滤器下游取样检查。

A.加油1000L

B.管线和过滤器壳体内残存的燃料排尽

C.加油结束

D.油罐存油加油完

答案

参考答案：B

问答题

有人说，现在的年轻人喊苦喊累，是因为社会竞争激烈的原因，你如何看
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单项选择题

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (41) or hubs, which just move the bits from one network to an identical network. One layer up we find bridges and switches, which operate at data link layer. They can accept (42) , examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two networks. If two networks have (43) network layer, the router may be able to translate between the packet formats. In the transport layer we find transport gateway, which can interface between two transport connections. Finally, in the application layer, application gateways translate message (44) . As an example, gateways between Internet E-mail and X.400 E-mail must (45) the E-mail message and change various header fields.

A．syntax

B．semantics

C．language

D．format
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