我国是一个多民族的国家。要了解回族的历史，最早应追溯到（）

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问题

A．汉朝

B．唐朝

C．元朝

D．清朝

答案

答案：C

根据所学，在元朝时期民族融合的产物是形成了一个新的民族回族，本题是课本基础知识的考查。

单项选择题

For each blank, choose the best answer from the four choices and write down on the answer sheet.
(71) is a channel’ s capacity which directly reflects the data transfer rate of the channel.
(72) functions in a NetWare network which is used to define addressing schemes.
(73) is a network layer device that supports multiple LAN interfaces and segments LANs into smaller collision and broadcast domains.
(74) is the popular LAN developed under the direction of the IEEE802.3.
(75) is a device which enables digital microcomputers to communicate across analog telephone lines.

A．The volume

B．The bandwidth

C．The noise

D．The delay

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多项选择题

国产减压阀有（）几种形式。

A.活塞式

B.波纹管式

C.薄膜式

D.热膨胀式

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