题干

如图所示,闭合开关S,灯泡L1、L2都能正常发光,两只电表都有示数,工作一段时间后,灯泡L1突然熄灭,L2仍然正常发光,两只电表均无示数,则故障可能是(   )

A:电压表短路

B:电流表断路

C:L1断路

D:L1短路

上一题 下一题 0.0难度 选择题 更新时间:2018-08-05 11:39:58

答案(点此获取答案解析)

B

同类题2

阅读理解

    Our “Mommy and Me” time began two years ago. My next-door neighbor and fellow mother, Christie, and I were out in our front yards, watching seven children of age 6 and under ride the bikes up and down. “I wish I could take one of my children out alone,” said Christie.

    Then we worked out a plan: When Christie takes one of her children out, I'll watch her other three. And when she watches two of mine. I'll take someone out.

    The children were extremely quick to accept the idea of “Mommy and Me” time. Christie's daughter, McKenzie, went first. When she returned, the other children showered her with tons of questions. McKenzie was smiling broadly. Christie looked refreshed and happy. “She's like a different child when there's no one else around,” Christie shared with me quickly. With her mother all to herself, McKenzie didn't have to make an effort to gain attention.

    Just as Christie had noticed changes in McKenzie, I also discovered something different in each of my children. For example, I am always surprised when my daughter, who is seldom close to me, holds my hand frequently. My stuttering (口吃的) son, Tom, doesn't stutter once during our activities since he doesn't have to struggle for a chance to speak. And another son, Sam, who's always a follower when around other children shines as a leader during our times together.

    The “Mommy and Me” time allows us to be simply alone and away with each child-talking, sharing, and laughing, which has been the biggest gain. Every child deserves to be an only child at least once in a while.

同类题5

阅读下文,完成下列小题。

    ①满天都是星光,火把也亮起来了。从山脚向上望,只见火把排成许多“之”字形,一直连到天上,跟星光接起来,分不出是火把还是星星。这真是我生平没见过的奇观。

    ②大家都知道这座山是怎样地陡了,不由浑身紧张,前后呼喊起来,都想努一把力,好快些翻过山去。

    ③“不要掉队呀!”

    ④“不要落后做乌龟呀!”

    ⑤“我们顶着天啦!”

    ⑥大家听了,哈哈地笑起来。

    ⑦在“之”字拐的路上一步一步地上去。向上看,火把在头顶上一点点排到天空;向下看,简直是绝壁,火把照着人的脸,就在脚底下。

    ⑧走了半天,忽然前面又走不动了。传来的话说,前面又有一段路在峭壁上,马爬不上去。又等了一个多小时,传下命令来说,就在这里睡,明天一早登山。

    ⑨就在这里睡觉?怎么行呢?下去到竹林里睡是不可能的。但就在路上睡么?路只有一尺来宽,半光接起来,分不出是火把还是星星。这真是我生平没见过的奇观。

    ②大家都知道这座山是怎样地陡了,不由浑身紧张,前后呼喊起来,都想努一把力,好快些翻过山去。

    ③“不要掉队呀!”

    ④“不要落后做乌龟呀!”

    ⑤“我们顶着天啦!”

    ⑥大家听了,哈哈地笑起来。

    ⑦在“之”字拐的路上一步一步地上去。向上看,火把在头顶上一点点排到天空;向下看,简直是绝壁,火把照着人的脸,就在脚底下。

    ⑧走了半天,忽然前面又走不动了。传来的话说,前面又有一段路在峭壁上,马爬不上去。又等了一个多小时,传下命令来说,就在这里睡,明天一早登山。

    ⑨就在这里睡觉?怎么行呢?下去到竹林里睡是不可能的。但就在路上睡么?路只有一尺来宽,半夜里一个翻身不就骨碌下去了么?而且路上的石头又非常不平,睡一晚准会疼死人。

    ⑩但这是没有办法的,只得裹一条毯子,横着心躺下去。因为实在太疲倦,一会儿就酣然入梦了。

    ⑪半夜里,忽然醒来,才觉得寒气逼人,刺入肌骨,浑身打着颤。把毯子卷得更紧些.把身子quán起来,还是睡不着。天上闪烁的星星好像黑色幕上缀着的宝石,它跟我们这样地接近哪!黑的山峰像巨人一样矗立在面前。四围的山把这山谷包围得像一口井。上边和下边有几堆火没有熄;冻醒了的同志们围着火堆小声地谈着话。除此以外,就是寂静。耳朵里有不可捉摸的声响,极远的又是极近的,极洪大的又是极细切的,像春蚕在咀嚼桑叶,像野马在平原上奔驰,像山泉在呜咽,像波涛在澎湃。不知什么时候又睡着了。

    ⑫黎明的时候被人推醒,说是准备出发。山下有人送饭上来,不管三七二十一,抢了一碗就吃。

    ⑬又传下命令来,要队伍今天无论如何爬过这座山。因为山路很难走,一路上需要督促前进。我们几个人又停下来,立刻写标语,分配人到山下山上各段去喊口号,演说,帮助病员和运输员。忙了一会,再向前进。

    ⑭走了不多远,看见昨晚所说的峭壁上的路,也就是所谓雷公岩的,果然陡极了,几乎是九十度的垂直的石梯,只有一尺多宽;旁边就是悬崖,虽然不很深,但也够怕人的。崖下已经聚集了很多马匹,都是昨晚不能过去、要等今天全纵队过完了再过去的。有几匹曾经从崖上跌下来,脚骨都断了。

    ⑮很小心地过了这个石梯。上面的路虽然还是陡,但并不陡得那么厉害了。一路走,一路检查标语。我渐渐地掉了队,顺便做些鼓励工作。