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问题 单项选择题

对于立克次体的特点，哪项是错误的（）

A.专性细胞内寄生

B.大小介于细菌与病毒之间

C.以节肢动物为传播媒介

D.可引起人畜共患疾病

E.对抗生素不敏感

答案

参考答案：E

单项选择题

Traditional Internet access methods like dial-up were so slow that host computers were connected to the dial-up （71） at the customer premise over slow （72） ports. PPP was designed to run directly over these serial links. But with the advent of broadband Internet （73）technologies such as ADSL and cable modems there has been a considerable increase in the bandwidth delivered to the end users. This means that the host computers at the customer premise connect to the （74） or cable "modem" over a much faster medium such as Ethernet.It also means that multiple （75） can connect to the Internet through the same connection.

72（）

A．parallel

B．digital

C．serial

D． variable
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单项选择题

液压夹紧装置与气压夹紧装置对比下列说法正确的是（）

A.液压油的不可压缩性使液压夹紧装置夹紧刚度高，工作平稳、可靠。

B.空气的不可压缩性使气压夹紧装置夹紧刚度高，工作平稳、可靠。

C.气压装置中的空气容易堵塞管路，装置维护复杂。

D.液压装置中的高压压力油不易泄漏，故液压元件制造较粗糙。
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