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问题 单项选择题

在网络设备配置和运维过程中，经常使用TFTP上传、下载交换机/路由器等设备的IOS。以下关于TFTP的描述中，错误的是______。

A．采用客户机/服务器方式，支持文件传输和用户交互功能
B．每次使用UDP 69端口传送小于等于512B的用户数据
C．既没有列目录的功能，也不能对用户进行身份鉴别
D．有相应的差错控制措施，每个报文需要应答

答案

参考答案：A

解析： TFTP是TCP/IP协议簇应用层的一个协议。它只支持文件传输而不支持交互。

完形填空
完形填空。

     Small talk is a good way   1   time and make friends. If you   2   to other countries, do you know what to
say to start small talk with local (当地的) people?
     In Britain, the best topic is the weather. British weather changes quite often. It's also a safe topic. You can
start small talk just by saying "It's a lovely day today, isn't it?"
     Besides the weather, it's good to talk about gardens    3   English people. For example, you could say
"Those roses look really beautiful,   4  ? "English people love their pets. So it's also nice   5   with "What a
lovely dog! What is its name?"
      In America, people like to talk about sports,   6   American football and basketball. They also talk about
clothes by saying"It's a nice shirt! Where did you get it?" The weather is a   7   topic there, too.
     Of course, there are also a lot of topics to avoid during small talk in western countries.
     Don't ask people"How old are you?" Age is usually a   8  , especially for women.  9   ask "How much
money do you make?" It makes people uncomfortable. Don't ask strangers whether they have a girlfriend   10 
 boyfriend. Politics and religions (宗教) are not good topic for two people who just met, either.

(   ) 1. A. kill    
(   ) 2. A. travel    
(   ) 3. A. in      
(   ) 4. A. don’t they
(   ) 5. A. begin     
(   ) 6. A. such that 
(   ) 7. A. dangerous
(   ) 8. A. friend    
(   ) 9. A. Never   
(   ) 10. A. and      		B. to kill    
B. listen     
B. at          
B. do they     
B. start       
B. the same as
B. difficult   
B. secret    
B. Please    
B. with     

C. killing      
C. talk        
C. with          
C. aren’t they  
C. to begin    
C. so that     
C. safe          
C. problem      
C. Ever         
C. but        

D. to killing   
D. want      
D. on              
D. are they   
D. starting     
D. such as   
D. hard        
D. question     
D. Usually      
D. or        
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选择题
在如图所示电路中，电源电动势E=6V，内阻r=1Ω，保护电阻R0=3Ω，滑动变阻器总电阻R=20Ω，闭合电键S，在滑片P从a滑到b的过程中，正确的是（　　）

A．滑动变阻器消耗的功率先减小后增大

B．滑动变阻器消耗的功率先增大后减小

C．滑动变阻器消耗的功率先减小后增大，再减小后增大

D．滑动变阻器消耗的功率先增大后减小，再增大后减小
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