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问题 单项选择题

插设塑料排水板可采用的设备是()。

A.潜孔钻机 

B.动力螺旋钻机 

C.喷粉桩机 

D.袋装砂井打设机

答案

参考答案：D

解析：

塑料排水板用插板机或与袋装砂井打设机共用打设。参见教材P20. 

单项选择题

Networks can be interconnected by different devices. In the physical layer, networks can be connected by. (31) 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 (32) , 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 (33) 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 (34) . As an example, gateways between Internet E-mail and X. 400 e-mail must (35) the e-mail message and change various header fields.

（35）是（）

A.analyze

B.parse

C.delete

D.create
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单项选择题

在第二次世界大战结束前夕，美国向日本长崎投掷原子弹的时间是1945年8月（）。

A.6日

B.9日

C.15日

D.8日
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