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问题 单项选择题

为提高班级民主管理，应建立以（）为本的班级管理机制。

A.教师

B.学生

C.学习

D.活动

答案

参考答案：B

解析：现代教育倡导建立以学生为本的现代班级管理机制，改变班主任为主的班级管理模式．建立班级民主管理的模式。

单项选择题

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (11) 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 (12) ,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 (13) network layer, the router may be able to translate between the packer 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 (14) . As an example, gateways between Internet e-mail and X.400 e-mail must (15) the e-mail message and change various header fields.

（12）是（）

A.frames

B.packets

C.packages

D.cells
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单项选择题

有机过氧化物必须放入（）后方可运输。（）

A、阻燃剂

B、还原剂

C、稳定剂

D、氧化剂
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