题干

如图所示,放在水平地面上的光滑绝缘圆筒内有两个带正电小球A、B,A位于筒底靠在左侧壁处,B在右侧筒壁上受到A的斥力作用处于静止.若筒壁竖直,A的电量保持不变,B由于漏电而下降少许重新平衡,下列说法中正确的是(   )

A:小球A对筒底的压力变小

B:小球A,B间的库仑力不变

C:小球A,B间的库仑力变小

D:小球B对筒壁的压力变大

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D

同类题2

阅读理解

    I have a friend named Monty Roberts who owns a horse ranch(牧马场). The last time I was there he told me his story. When he was young, his family was too poor to have a house to live in.As a result , when he was in high school, all the students were asked to write a paper about what they wanted to be and do when they grew up. That night he wrote a seven-page paper describing his goal of owning a horse ranch. He also drew a picture to show a 4,000-square-foot house that would sit on a beautiful farm. The next day he handed it in to his teacher. Two days later he received his paper back. On the front page was a large red F. Roberts asked, “Why did I receive an F?” He teacher said, “This is an unrealistic dream for a young boy like you. Owning a horse ranch requires a lot of money.” Then the teacher added, “If you will rewrite this paper with a more realistic goal, I will reconsider your grade.”

    The boy went home and thought about it for a long and hard time. He asked his father what he should do. His father said, “ Look, son, you have to make up your own mind on this. However, I think it is a very important decision for you.”Finally, after sitting with it for a week, the boy turned in the same paper, making no changes at all. He told his teacher “you could keep the F and I still keep my dream”.

    He tells me this story because I am sitting in his 4,000-square-foot house in the middle of the 200-acre horse ranch. “I still have that school paper now.” He added, “The best part of the story is that two years ago that  teacher brought 30 kids to camp out on my ranch for a week.” When the teacher was leaving, he said, Look, Monty, I can tell you this now. When I was your teacher, I was something of a dream stealer.During those years I stole a lot of kids' dreams. Luckily, you had enough gumption not to give up on yours. .”

同类题5

阅读下面的文字,完成下列各题。

灯笼红

牛汉

    ①我们家乡有一种香瓜叫做“灯笼红”。这瓜熟透了以后,瓤儿红得像点亮的灯笼。我的曾祖母就像熟透了灯笼红。她面孔黧黑,布满老树皮般的皱纹,可是心灵却如瓜瓤那样又红又甜。我在童年时期见过不少这样的老人,他们经历了艰难的一生,最后在生命的内部酿出并积起隽永而仁慈的美好性灵。

    ②曾祖母至少活到八十岁以上,我四岁那年,她无疾而终。我跟她在一盘大炕上挨着睡,她死的那天晚上,把我的被褥铺好,像往常那样,如打坐的僧人,久久不动地盘腿坐在上面,为的是把被窝焐得暖暖和和的。我光身子一出溜钻进被窝,曾祖母隔着被子抚拍我好半天,直到我入睡为止。那时正是严寒的冬天。当我在温暖的被窝里做着梦的时候,曾祖母在我身边平静地向人生告别了。

    ③我睡得死,醒来时天大亮。平时曾祖母早已起床下地,坐在圈椅里跟祖母说话,今天为甚仍稳睡着?侧脸一瞧,一双绣花的新鞋露在曾祖母的被头外面,不是过大年,为甚穿新鞋?还有,她怎么头朝里睡?我愣怔地坐起来,看见姐姐立在门口嘤嘤地哭泣,屋里有几个大人靠躺柜立着。我坐起来,刚喊了声“老娘娘”(家乡对曾祖母这么叫,第一个“娘”读入声),就被一双有力的手臂连被窝一块抱走,送到父母住的屋子里。我哭着,我并不晓得曾祖母已死,喊着“老娘娘……”这时我才听见几个姐妹也都哭喊着“老娘娘”。

    ④我家的大门口平放着一扇废弃的石磨,夏日黄昏,曾祖母常常坐在上面。我从远远的街角一露面,她就要扯着嗓门喊我:“汉子,汉子,快过来!”我们家乡女人把丈夫才叫“汉子”。曾祖母“汉子汉子”的叫我,引得过路的人狂笑不止。这个细节我一直没有忘记。我跑到她身边,她牵着我的手走进大门。一进大门,有一间堆放麦秸的没门没窗的房子,麦秸经过碌碡压过以后很柔软,我们叫“麦滑”。当年的麦秸都有股浓馥的太阳味儿,我自小觉得凡太阳晒过的东西都有一股暖暖的甜味,在收割季节的庄稼叶子上能闻到,在地里的土坷垃上能闻到,而熟透的“灯笼红”香瓜散发出的太阳味儿最浓。

    ⑤曾祖母叮咛我:“你看着,不要让人来。”我心里全明白,假装着懵懵懂懂,隔着麦秸,我早闻到诱人的灯笼红的香味。曾祖母跪在麦秸上,双手往里掏,掏得很深,半个身子几乎埋进麦秸里,麦秸里沉聚的芬芳的太阳味儿被扬了起来,刺得鼻孔直痒痒。她终于掏出三五个“灯笼红”,逐个闻一闻,挑出其中最熟的一个递给我,把剩下那几个又深深地寄在麦秸里面。家乡话中“寄”是藏匿的意思。甜瓜寄在麦秸里两三天,能把半熟的瓜酿得全熟,浓浓的香味溢出瓜皮。香味正如同灯放射出的光芒,只不过不像灯光能看得见。其实跟看得见也差不多,一闻到香味就等于看见了红烁烁的瓜瓤了。我们回到大门口磨盘上坐着,曾祖母眼瞅着我一口口地把瓜吃完。

    ⑥我连曾祖母的姓氏和名字都不知道,她留给我的只有上面说的一些梦一般的事迹。隐约地记得她个子很矮小,穿的袄肥而长,宽大的袖口卷起半尺来高,里面总寄放些小东西,她会从里面给我掏出几颗醉枣或麦芽糖。对曾祖母的手我还有记忆。她总用干涩的手抚摸我的面孔,晚上当我钻进被窝,她的手伸进被窝久久地缓慢地抚摸着我,从胸口直抚摸到脚心,口里念念有辞:“长啊,长啊!”我现在仍能隐隐感触到她的手微微颤动着,在我的生命的里里外外……别的,关于她,我什么也记不得了。她早已隐没进了无法忆念的像大地一般深厚的历史的内腔之中了。

    ⑦听说曾祖母年轻时性子很刚烈,说一不二,村里有个姓王的武举人(是全县有名的摔跤场的评判),都怕她三分。到了晚年,她却异常的温厚,像收完了庄稼的一快田地,安静地等着大雪深深地封盖住它。她从人间隐没了,回到生养她的浑然无觉的大自然。大自然因他们(无以数计)生命的灵秀和甜美而更加富有生育的能力。