题干

在图所示的电路中,电源电压保持不变,闭合电键S电路正常工作,一段时间后,发现电路中至少有一个电表的示数变大,故障发生的电阻R1、R2上,其他元件仍保持完好.

①用一个完好的小灯替换R2后,小灯____(选填“一定发光”或“可能发光”)

②在原路故障电路中,将电流表A与R1位置互换后,电压表V的示数不发生变化,电路中可能存在的故障是____.

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答案(点此获取答案解析)

一定发光,R2断路(或R1短路或R2断路且R1短路)

同类题1

阅读下面短文,掌握其大意,然后从各题所给的A、B、C、D四个选项中选出最佳选项,并将选定答案的字母标号填在题前括号内。

My car and my best friend

    For most, getting your first car opens up a new world of freedom and allows you to go wherever you want, whenever you want. Getting a car did 1 this for me, and it also brought my best friend and me 2. But then it tore us apart (分开).

    My best friend lives three minutes from my 3. Since her 4 is in late summer, seven months behind mine, I basically became her 5 when I turned 16 in December.

    And so I 6 her up for school and took her home. We made ice-cream 7, went shopping and to the movies all in my car. I would drive to her house just to sit on her bed, read magazines and have a good laugh. I went to her house so 8 that she gave me a key 9 her house.

    A week after I got my license (驾照), she was with me 10 I had my first accident. She was there and 11 me and we kept it a 12, since I didn't want people to 13. From then on, through thick and thin (共患难), it was just me , my car and my best friend.

    High school is a time of 14, but I couldn't 15for a long time 16we became so distant (疏远) after being so close. My friend waited three months after her birthday to get her dream car:a green 2004 Beetle. With its 17, the passenger seat of my car became 18. Our car trips became less frequent (频繁的) 19 I didn't even drive down her street.

    It's funny how a car can change a relationship so much. I had wanted her to get a car, but once she did, I 20it. I wanted her friendship back, even if it couldn't be the same.