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问题 单项选择题 A1/A2型题

总补体活性测定试验中，溶血素用量为（）

A.0.5单位

B.1.0单位

C.1.5单位

D.2.0单位

E.4.0单位

答案

参考答案：D

解析：总补体活性通过溶血试验测定，溶血素为定量，采用两个溶血素单位。

单项选择题 B1型题

视瞻昏渺出自（）

A.《证治准绳·七窍门》

B.《审视瑶函》

C.《秘传眼科龙木论》

D.《眼科纂要》

E.《目经大成》
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问答题

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (1) 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 (2) , 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 (3) 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 (4) . As an example, gateways between Internet e-mail and X.400 e-mail must (5) the e-mail message and change various header fields.

A．reapers

B．relays

C．connectors

D．modems
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