搜题请搜索小程序“爱下问搜题”
问题 单项选择题

八度音程的频率比为（）

A.3：2

B.1：2

C.4：3

D.6：5

答案

参考答案：B

解析：当两音相差半音，那么高音的频率就是低音的约1.06倍。当两个音相差一个全音，那么高音的频率是低音的1.06~2倍。当两音相差1.5个全音，那么高音的频率是低音的1.06—3倍。直到两音相差8度（12个半音），高音的频率是低音的1.06—12倍，刚好等于2

单项选择题 A1/A2型题

肾病综合征低白蛋白血症的主要原因为（）

A.肾小球滤过膜对血浆蛋白的通透性增加

B.肾小管的重吸收功能障碍

C.蛋白质分解代谢增强

D.蛋白质摄入不足

E.肝脏合成白蛋白障碍
查看答案
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 network layer, we have routers that can connect two networks. If two networks have (33) network layer, the muter 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 (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.

（32）是（）

A.frames

B.packets

C.packages

D.cells
查看答案