【简答题】在电信网中,本地环路由市话端局或远端模块到用户终端之间的机线设备构成,主要完成交叉连接、复用和传输功能,一般不含交换功能。在现代电信网中,本地环路已由()替代。
【单选题】下列叙述中,正确的是()。
B.
计算机病毒主要通过读/写移动存储器或Internet网络进行传播
C.
只要删除所有感染了病毒的文件就可以彻底消除病毒
D.
计算机杀病毒软件可以查出和清除任意已知的和未知的计算机病毒
【单选题】听力原文:W: Where do you want me to drop you off? M: Right here is fine. Q: What will the man probably do? (15)
【单选题】用N A 表示阿伏加德罗常数.下列叙述不正确的是( )
B.
标准状况下,22.4L己烷价键数目为19N A
C.
92g乙醇与足量的金属钠反应,生成氢气的分子数为N A
D.
常温下,14g乙烯和丙烯的混合物中总原子数为3N A 个
【单选题】一Do you know where Liberty Street is? 一 It's off Oak Street, near the park. —____. 一 I don't know exactly. Perhaps every five minutes or so.
A.
The park? Which one do you mean?
B.
Do you have any idea where Pine Street is?
C.
By the way, do you know how often the Number 5 bus runs normally?
【单选题】下列叙述正确的是( )
A.
金属受外力作用时常常发生变形而不易折断,是由于金属原子之间有较强的作用
B.
通常情况下,金属中的“自由电子”会发生定向移动而形成电流
C.
金属是借助“自由电子”的运动,把能量从温度高的部分传到温度低的部分
【单选题】Where should you switch off your phone? [音频]
A.
Stop at the side of the road before answering the call.
B.
With a cell phone, they can keep in touch with friends, family and co-workers wherever they go.
C.
Switch off phones in meetings, movies, restaurants, and any other place where it might cause a distce.