题干

将欧姆定律的公式I=U/R变形得到R=U/I,关于此式物理意义,下面说法中正确的是(    )

A:导体的电阻与它两端的电压成正比,与通过它的电流成反比

B:导体中通过的电流越大,则电阻越小

C:加在导体两端的电压越大,则电阻越大

D:导体的电阻等于导体两端的电压和通过它的电流之比

上一题 下一题 0.0难度 选择题 更新时间:2016-07-12 07:15:49

答案(点此获取答案解析)

D

同类题2

阅读下面的文字,完成下列小题。

宗璞:且将秃笔长相守

李冰

    何谓“南东西北”?宗璞四卷本《野葫芦引》系列长篇小说《南渡记》《东藏记》《西征记》《北归记》是也。宗璞本名冯钟璞。出身书香门第,其父冯友兰是众所周知的大哲学家。宗璞上世纪50年代毕业于清华大学外文系,60年代后长期在外国文学研究所工作,中外文化的滋养使得她“腹有诗书气自华”。宗璞的作品有小说和散文,还有童话和译著。她算不得“多产作家”,却是“多奖作家”,曾获茅盾文学奖、全国优秀中篇小说奖、全国优秀短篇小说奖、全国优秀散文(集)奖等。

    宗璞住在北京大学燕南园57号冯友兰先生的老屋内。这是一座青砖黛瓦的小院,号“三松堂”。如今,房舍虽旧,仍能看出当年的格局:院中三棵松,室内万卷书。宗璞生活在我国高级知识分子群中,接触了众多的文化名家、巨匠,因此,知识精英是她创作的独特对象。抗战时期,她随父南迁昆明,在西南联大度过八年。这便是反映中国知识界抗日系列长篇小说《野葫芦引》的丰厚生活基础。她在书中生动塑造了一批忧国忧民的知识分子形象,深刻细腻刻画了他们的人格操守和情感世界。

    说起创作,宗璞着实不易。写《东藏记》时,她已病痛在身,写了七年,与疾患抗争了七年。她曾有感而发,作了一首散曲:“人道是锦心绣口,怎知我从来病骨难承受。兵戈沸处同国忧。覆雨翻云,不甘低首,托破钵随缘走。悠悠!造几座海市蜃楼,饮几杯糊涂酒。痴心肠要在葫芦里装宇宙,只且将一支秃笔长相守。”这亦正亦谐的散曲正是她心境的写照,反映了作家的生命价值、灵魂皈依和坚强意志。

    一天,宗璞住院了,她穿着病号服倚在床头,因高血压脸色潮红。她忙着赶写《北归记》,累着了,血压高,头晕。朋友劝她不要太拼了。她说:“放不下,小说里的故事和人物在脑海里翻腾,挥之不去,不写完睡不着觉。”

    去年春夏时分,宗璞突然脑出血,这次病得危急,在重症监护室里熬了两周,又住了三个月院。当时,宗璞曾悲观地认为自己无法再继续写作了。可是当身体稍有好转,她又重操旧业,开始像蜗牛一样缓缓地爬在格子里,恢复了每天早晨的写作。写一会儿歇一会儿,头晕就去吸氧。有人问她,抱病苦耕的动力何来?她回答:我有责任把那个时代的知识分子所想、所为记录下来,呈现给现在的读者。

    宗璞不止一次视网膜脱落,几经手术右眼保留了0.3的视力,左眼几乎失明。她戏称自己是“半盲人”,“用放大镜也只能看清拳头大的字,写得很苦,进度很慢”。她说:“现在每天只能写一二百字。不是手写,是口述,别人帮助记下来,然后念给我听,我再修改。”也就是说《北归记》的写作全由宗璞口述,记录后由助手反复念,她反复改,这样一段一段、一章一章磨出来。她这是用生命在苦吟炼句啊,每天百余字在腹中推敲,用写诗的功夫写小说。宗璞曾说过:“读小说是件乐事,写小说可是件苦差事。不过苦乐也难截然分开。”她还表示:“下辈子选择职业,我还要干这一行。”

    创作出传世精品《钢铁是怎样炼成的》的苏联作家奥斯特洛夫斯基和美国著名女作家海伦·凯勒都是从小就刻在我们心里的最受尊敬的人。中国作家群中也不乏这样“身有疾、志弥坚”值得我们敬佩并为之骄傲的作家,宗璞是一个。

(选自《人民日报》,有删改)

【相关链接】①宗璞曾说,她走上文学之路,得益于父亲冯友兰。冯老虽是哲学家,于文学却颇有造诣,能写旧诗,很有文采,常常对文艺有独特见解。宗璞自小耳濡目染,受益匪浅。《南渡记》出版后,冯老曾勉励道:“百岁继风流,一脉文心传三世;四卷写沧桑,八年鸿雪记双城。”(徐小斌《清静淡泊的宗璞》)②宗璞以她细密从容的叙述方式,建立起优美温婉的语言风格。众多的人物命运和世相心态,在看似平淡的生活情境和细节中缓缓展开,伏有大气磅礴的布局。宗璞笔下的战争没有刀光剑影,却烙刻了深重的精神创痕,并具有一种柔性的书卷气息。读《东藏记》和《紫藤萝瀑布》这样隽永而精致的作品,真是受益又享受。(百度百科)

同类题3

下面文章中有五处需要添加首句。请从以下选项(A、B、C、D、E 和F)中选出符合各段意思的首句。选项中有一项是多余选项。

A. Teach children not to talk to strangers

B. Tell students to follow the school rules

C. Talk to your children about their day

D. Keep an eye on your children's Internet use

E. Teach children not to work out problems by fighting

F. Tell your children a safe way to walk to school or the bus stop

    Students spend more time at school than anywhere else. At school, children need a safe and comfortable environment to help them learn. By doing the following, parents can help make sure children have a good school life.

    ____. Ask your children if they see anyone bullied(被欺负), if they are bullied, or if anything else makes them feel uncomfortable. Look for warning signs, such as a sudden drop in grades or a loss of friends.

    ____. Tell children that fighting could lead to them getting hurt, or hurting someone else. Tell them about other ways they can solve a problem, such as walking away or telling to teachers or the adult you know well.

    ____. Talk to your children about what they do online—what websites they visit, who they email, and who they chat with. Let them know they can talk to you if anything they see online makes them uncomfortable.

    ____. Teach children to follow traffic lights and rules when walking or biking. Stress that they should cross the street at crosswalks.

    ____. Don't go anywhere with them, or accept gifts from them when you don't know. If they see a stranger hanging around or in their school, they should tell the people that you know.