现有两只定值电阻R1、R2,已知R1=2R2,一个能向外提供恒定电压的电池组,还

题型:填空题

问题:

现有两只定值电阻R1、R2,已知R1=2R2,一个能向外提供恒定电压的电池组,还有若干导线.

(1)试把以上器材分别画在下页的甲图和乙图中标有A、B、C、D字样的接线柱上,使它们各自组成一个完整的电路(所用电表均为理想电表,量程也总能满足要求).并能满足以下要求:当电键S断开时,电表指针偏转到某一位置,当电键S闭合时,电表的示数为S断开时的3倍.

(2)在满足以上要求的情况下,图甲中电键S断开和闭合两种情况下,外电路消耗的电功率之比为______.

(3)在满足以上要求的情况下,图乙中电键S断开和闭合两种情况下,R2上消耗的电功率之比为______.

考点:电功电功率
题型:填空题

阅读理解。

     Do you like children? Do you have free (空闲的) time in the afternoon?  We need a babysitter (保姆) 

 for our son. He's five years old. The working time is Monday to Friday, 3:00 pm to 6:00pm. ( $ 5 an

 hour) We need help with: Looking after our son; Reading to him; Playing with him.

     You must work at our house. We live in Changchun, near the Culture Square (文化广场). Please call 

 Mr. Green at 5638-2949.

1. From Monday to Friday, the babysitter can work _____ every day.

    A. one hour

    B. two hours

    C. three hour 

    D. four hours

2. Which is NOT the work that the babysitter needs to do?

    A. Cooking for the child.

    B.  Playing with the child.

    C.  Reading books to the child.

    D. Looking after the child.

3. The babysitter must work _____.

    A. at the babysitter's house    

    B. at Miss Green's school.

    C. at Mr. Green's house.      

    D. at the Culture Square

4. The child in the ad (广告) is _____.

    A. 15 months old  

    B. 15 years old

    C. 5 months old  

    D. 5 years old

5. If (如果) ______, you can get the job.

    A. you like children, but you have no time in the afternoon

    B. you like children, but you don't know how to play with them

    C. you're good with children and you're free in the afternoon

    D. you can play with children but you don't know how to read

题型:填空题

如图所示,电源电动势E=10V,R1=3Ω,R2=6Ω,C=30μF,闭合开关K,电路稳定后,路端电压U=9V,求:

(1)电路稳定后通过R1的电流;

(2)电源的内阻r;

(3)若开关K断开,求这以后通过R2的总电量.

题型:填空题

过滤系统终端过滤芯的完整性测试试验一定需要在线监测吗?而压缩空气系统、制氮系统的滤芯如何测试和清洁?(FL1)

题型:填空题


阅读下列说明,回答问题1至问题4,将解答填入对应栏内。
【说明】
若设置域名解析服务器,已扣该文件服务器上文件named.boot 的内容如下:
Directory/var/named
Cache named.root
Primary 0.0.127 in-addr.arpanamed.local
Primary net.edu.ch net.edu.crt.hosts
Primary 58.112,202. in-addr.arpa net,edu.cn.rev
Secondary edu,ch 202,112.0.33 edu,cn.2nd
Forward 202.,112.0.35

【问题2】
当DNS服务器启动后,如何验证其是否正常工作

题型:填空题

大修后机械寿命缩短的原因及采取的措施有哪些?

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