问题 计算题

(10分)如图所示,一小型发电站通过升压变压器B1和降压变压器B2把电能输送给用户(B1和B2都是理想变压器),已知发电机的输出功率为500kW,输出电压为500V,升压变压器B1原、副线圈的匝数比为1﹕10,两变压器间输电导线的总电阻为2Ω,降压变压器B2的输出电压为220V。求:

(1)输电导线上损失的功率;

(2)降压变压器B2的原、副线圈的匝数比。

答案

(1)    (2)

题目分析:(1)原副线圈电压比等于匝数比,对升压变压器:,即        2分

输电线的电流:              2分

损失的功率:         2分

(2)降压变压器的输入电压              2分

降压变压器匝数比:               2分

单项选择题 B1型题
翻译题

完成句子。

阅读下列各小题,根据每句后的汉语提示,用句末括号内的英语单词完成句子.

1.Smell the flowers before you go to sleep,____________________ a sweet dream.(have)

睡觉之前闻着花香,你会做一个美梦.

2.With Father's Day around the corner, I have taken some money out of the bank_______________

_____my dad. (buy)

父亲节快到了,我从银行取了些钱给爸爸买礼物.

3.____________________my classmates, I read the same excitement in their eyes.(look)

看着我的同学们,从他们的眼里我读出同样的兴奋.

4.Lots of rescue workers were working around the clock,____________________supplies to Yushu, Qinghai Province after the earthquake. (send)

地震后,许多救援工人不分昼夜地工作,给青海玉树发送救援物资.

5.The retired man donated most of his savings to the school damaged by the earthquake, ________________the students to return to their classrooms.(enable)

这位退休老人把自己大部分的积蓄捐给了被地震毁掉的学校,使学生们能够重新回到教室.

6.There were many talented actors out there just____________________.(wait; discover)

那儿有很多有天赋的演员等待着被人发掘.

7.She had a picture taken ____________________on either side of the longitude line.(stand)

她站在经度线的两边分别照了一张相.

8.It is essential that the program ____________________into computer.(load)

把这个程序输入电脑很有必要.

9.It seemed incredible that such a little boy ____________________two foreign languages.(acquire)

这么小的男孩竟然学会了两种外语真是令人难以置信.

10.I have told you the truth. Must I keep ______________?(repeat)

我已经告诉你真相了.我还得不停地重复吗?