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问题 判断题

生物的环境是指生物的生存地点。                               ( ) 

答案

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题目分析: 自然环境中，各种因素影响着生物，环境中影响生物生活的各种因素叫环境因素，分为非生物因素和生物因素。非生物因素包括：光、温度、水、空气、土壤等。生物因素是指环境中影响某种生物个体生活的其他所生物，包括同种和不同种的生物个体

考点:生物与环境的关系。

单项选择题

听神经瘤手术时，在分离切除肿瘤过程中最容易损伤的血管是（）

A.小脑后下动脉

B.小脑前下动脉

C.小脑上动脉

D.椎动脉

E.基底动脉
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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 (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（）

A.frames

B.packets

C.packages

D.cells
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