[题目]一台发电机最大输出功率为4 000 kW.电压为4 000 V.经变压器T1升压后向远方输电.输电线路总电阻R＝1 kΩ.到目的地经变压器T2降压.负载为多个正常发光的灯泡(220 V.60 W).若在输电线路上消耗的功率为发电机输出功率的10%.变压器T1和T2的耗损可忽略.发电机处于满负荷工作状态.则( )A．T1原.副线圈电流分别为103 A� 题目和参考答案——青夏教育精英家教网—

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【题目】一台发电机最大输出功率为4 000 kW，电压为4 000 V，经变压器T1升压后向远方输电。输电线路总电阻R＝1 kΩ。到目的地经变压器T2降压，负载为多个正常发光的灯泡（220 V，60 W）。若在输电线路上消耗的功率为发电机输出功率的10%，变压器T1和T2的耗损可忽略，发电机处于满负荷工作状态，则（）

A．T1原、副线圈电流分别为103 A和20 A

B．T2原、副线圈电压分别为1．8×105 V和220 V

C．T1和T2的变压比分别为1∶50和40∶1

D．有6×104盏灯泡（220 V，60 W）正常发光

【答案】ABD

【解析】输电线上消耗的功率P线＝R＝400 kW，则I2＝＝20 A，又P1＝U1I1，则I1＝＝103 A，故A正确；T1的变压比＝＝，又P＝U1I1＝U2I2，得U2＝2×105 V，输电线上损失电压U线＝I2R＝2×104 V，则T2原线圈的输入电压U3＝U2－U线＝1．8×105 V，又灯泡正常发光，T2的副线圈的电压为220 V，B正确；T2的变压比＝＝，C错误；根据U3I2＝60n，解得n＝6×104，D正确。

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【题目】短文改错

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：

1. 每处错误及其修改均仅限一词；

2. 只允许修改10处，多者（从第11处起）不计分。

The summer holiday is coming. Our class has a discussion about what to do during the holiday.
Some are in favor of staying at home. They think it’s both convenience and comfortable. What’s more, they can to save money for other purposes. But they will lose chance of getting to know the outside world. Besides, others prefer to go out for traveling, that can increase their knowledge and broaden their horizons. But they will spend more money or meet some difficulties while traveling.
In my opinion, it would be much good to stay at home, for I can do how I like, such as reading books, watching TV, and help my parents with the housework.

【题目】如图所示为一速度选择器，也称为滤速器的原理图。K为电子枪，由枪中沿KA方向射出的电子，速率大小不一。当电子通过方向互相垂直的匀强电场和磁场后，只有一定速率的电子能沿直线前进，并通过小孔S。设产生匀强电场的平行板间的电压为300 V，间距为5 cm，垂直于纸面的匀强磁场的磁感应强度为0．06 T，问：

（1）磁场的指向应该向里还是向外？

（2）速度为多大的电子才能通过小孔S?

【题目】短文改错

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：

1. 每处错误及其修改均仅限一词；

2. 只允许修改10处，多者（从第11处起）不计分。

Dear friends,

It is real a good chance to have met all of you here. We have spent several precious weekend in learning in the English Club. Although we have been members for a short period of times, we have made a great progress. That is because we are all very actively and the activities are not only enjoyable and also helpful. Besides, the foreign teachers here work hard and try his best to make the activities lively and interested. I am very pleased to say that all of us greatly improved our spoken English so far. I am looking forward to see all of you again in the near future!