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问题 选择题

欲除去下列物质中混入的少量杂质（括号内物质为杂质），错误的是 [ ]

A．乙酸乙酯（乙酸）：加饱和Na2CO3溶液，充分振荡静置后，分液

B．乙醇（水）：加入新制生石灰，蒸馏

C．溴苯（溴）：加入NaOH溶液，充分振荡静置后，分液

D．乙酸（乙醇）：加入金属钠，蒸馏

答案

答案：D

多项选择题

为提高报批效率，客户分类报批事项可采用表式上报，无需撰写调查审查报告，但下列哪些报批事项仍需撰写报告？（）

A.存量客户分类复核

B.新营销客户分类

C.行业属性修改调整

D.突破政策标准分类
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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 (71) 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 (72) ，examine the MAC address and forward the frames to a different network while doing minor protocol translation in the process in me network layer，we have routers that can connect two networks，If two networks have (73) network layer，the router may be able to translate betweenthe 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 (74) ．As an example，gateways between Internet e-mail and X，400 e-mail must (75) thee-mail message and change various header fields．

A．syntax

B．semantics

C．language

D．format
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