题干

一通电直导线用细线悬挂于匀强磁场中,磁场及电流方向如图.通电导线所受安培力的方向是(  )

A:水平向左

B:水平向右

C:竖直向上

D:竖直向下

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答案(点此获取答案解析)

D

同类题1

阅读下面文言文,完成下列小题。

谏说之难洪迈

    韩非作《说难》,而死于说难,盖谏说之难,自古以然。至于知其所欲说,迎而拒之,然卒至于言听而计从者,又为难而可喜者也。

    秦穆公执晋侯,晋阴饴甥往会盟,其为晋游说无可疑者。秦伯曰:“晋国和乎?”对曰:“不和。小人曰必报仇,君子曰必报德。秦伯曰:“国谓君何?”曰:“小人谓之不免,君子以为必归;以德为怨,秦不然。”秦遂归晋侯。

    秦伐赵,赵求救于齐,齐欲长安君为质。太后不肯,曰:“复言者,老妇必唾其面。”左师触龙愿见,后盛气而揖之入,知其必用此事来也。左师徐坐,问后体所苦,继乞以少子补黑衣之缺。后曰:“丈夫亦爱怜少子乎?”曰:“甚于妇人。”然后及其女燕后乃极论赵王三世之子孙无功而为侯者祸及其身后既寤则言长安君何以自托于赵?于是后曰:“恣君之所使。”长安君遂出质。

    范雎见疏于秦,蔡泽入秦,使人宣言感怒雎,曰:“燕客蔡泽,天下辩士也。彼一见秦王,必夺君位。”雎曰:“百家之说,吾既知之,众口之辩,事皆摧之,是恶能夺我位乎?”使人召泽,谓之曰:“子宣言欲代我相,有之乎?”对曰:“然。”即引商君、吴起、大夫种之事。雎知泽欲困己以说,谬曰:“杀身成名,何为不可?”泽以身名俱全之说诱之,极之以闳夭、周公之忠圣。今秦王不倍功臣,不若秦孝公、楚越王,雎之功不若三子,劝其归相印以让贤。雎竦然失其宿怒,忘其故辩,敬受命,延入为上客。卒之代为奏相者泽也。

    秦始皇迁其母,下令曰:“敢以太后事谏者杀之。”死者二十七人矣。茅焦请谏,王召镬将烹之。焦数以桀、纣狂悖之行,言未绝口,王母子如初。

    吕甥之言出于义,左师之计伸于爱,蔡泽之说激于理,若茅焦者真所谓剧虎牙者矣。范雎亲困穰侯而夺其位,何遽不如泽哉丨彼此一时也。

——节选自《容斋随笔》

同类题3

阅读理解

    Teachers in some secondary schools in Britain are worried that their job may become impossible shortly unless something can be done to restore discipline in the classrooms. In the problem schools, mostly in large cities, a small minority of teenage pupils disturb lesson to such an extent that the teacher can no longer teach their classes effectively.

    Some people consider that the permissive (随意) nature of modern society is responsible for such kind of behavior. Small children who are continuously encouraged to express themselves without reservation are naturally unwilling to accept school discipline when they grow older. Furthermore, modern teaching techniques) which appear to stress personal enjoyment at the expense of serious study work, might be teaching the child to put his own interests before his duties to the community in which he lives.

    Perhaps the problem can be solved by improving facilities for the moral guidance of these difficult children or by better cooperation between the schools and the parents—for the parents may be mainly responsible for the bad behavior of their youngsters. Violence at home, violence and crime on TV make some children turn violence themselves.

    But some of the teachers believe that there ought to be a return to more “old fashioned” methods. At present, in some school teachers are even not allowed to punish a child who does something bad and wrong. Physical punishment is not permitted now. People are too soft on children these days. It seems that children can do whatever they like at school while the teachers can't do anything to punish them. I don't know why the schools authority abandoned some of the effective punishments that worked well. Things like that didn't happen when we were at school because the teachers kept those problem students under control by using a stick.