题干

下列与化学反应能量变化相关的叙述正确的是

A:生成物总能量一定低于反应物总能量

B:放热反应的反应速率总是大于吸热反应的反应速率

C:根据盖斯定律,可计算某些难以直接测定的反应的△H

D:同温同压下,H2 (g)+ Cl2 (g) =' 2HCl' (g) 在光照和点燃条件的△H不相同

上一题 下一题 0.0难度 选择题 更新时间:2019-10-31 03:11:44

答案(点此获取答案解析)

C

同类题2

阅读下文,回答问题。

要命的书

孙珉

       ①我常常怕枕边摞得高高的书掉下来,把我砸个半死,甚至一命呜呼。

       ②这惧怕由来已久。小时候家里房子小,墙上钉上两根铁扦,架上块长木板,书一摞摞地堆在上面,顶到了屋顶。我们个子小,须站到桌子上才能够到书。书平放着,只能看到切口,看不到书脊,就一本本抽出来翻。书本来就不多,抽完一摞就记住了名子,单看厚薄就知是那本书。只是在抽底下的书时,用劲一拉,整摞书便扣在脑袋上,落得个灰头土脸。要是给函装的书砸了,头上肯定会起个青包。那函多是爸爸自己做的,不用硬纸板,用的是木板,耐摔。父母吵架,并不动手,妈妈的火上来了,会用木棒将木板子掀起来,只听轰天的霹雳过后,那些书便从天堂被打到地狱,残鳞败甲落了一地。这是绝招,老头子只好耐着性子一本本收拾,一张纸片都舍不得丢,收拾完了,气也消了,看着自己这些久经考验的命根子,发呆。

       ③待我上了大学,在图书馆陡然见了那么多好书,都是久闻大名,如雷贯耳、皓月当空的古今圣贤的作品,就一本本往屋里搬,借只能借 3 本,啃得动的立刻啃掉换新的,啃不动的就多留几天,搁在枕边伴我入梦,真盼着夜里一缕精魂袅袅飘入灵府,通我心窍,启我智慧,让我通体发光,可惜,让我通体发光的还是早晨八九点钟的太阳。到了书店,见到这些啃不动的书立刻买下,还掉公家的。不多时候,床上便摞满名著,特别唬人,我乐的是我终于有了这些耐用消费品,现在放在这里,更像是我的睡床之宝、知识权威,不仅让我静穆庄严,也引得不少人纷纷在床头立起知识神龛,每夜临睡前翻上几翻,算是拜了大礼,像是基督徒饭前的祈祷。然后找上一本好看的过瘾。这些书依旧威严地躺在那里,而且越摞越高,我的压力也就越来越大,个个都可敬可爱,却又不知道怎样去获得这些书的青睐,既不用功,又想个个都爱,不可能的事。读到天花乱坠,醒醐灌顶的时候也有。这时,就痴痴地想个不休,觉得自己做了这些书的主子,很神气了几天,争论时底气也壮。可过不久翻到让我开窍的地方,竟又是山重水复,雾气茫茫,不觉呆了,不知是我错了,还是这些大师老奸巨滑,戏耍无知顽童。久而久之,我们也不敢造次了,有文字处多留住眼,有可想处多定些神。书多没处放了,就与同学一道去建筑工地,每人偷一块脚手架的长木板,白纸包好架在床上,将这些书供奉起来。哈,那真是知识的银河,璀璨的群星,他们主宰着知识的星空,我们须仰视才看得见。

       ④毕业时,大包小包多是书。虽听说有人大发牢骚,说书又重又沉,可真正把书卖掉的并不太多。对着提着麻袋收书的小贩,他们都很吝啬,常让小贩扫兴而去。一位即将奔赴沿海经商的同学,恋恋不舍地将一本本书精心放在箱子里,我还从未看到他这么珍惜书。那里面有一套几乎全新的黑格尔著作,特别扎眼,国内出的译本几乎他都全了。他抚摸了许久,最后还是说:“老黑,走吧”。那神情像是和黑格尔商量一同下海。

       ⑤如今,我还是掉进了文字之海。整日满眼都是字,书是越读越多,头发是越读越稀,眼是越读越坏。读完了就把字拿来卖,依旧是书生的那一点点能耐。只是经过的事变成的字,如焊进脑子里,不像在海中游乏了,上岸抖落一下便抖尽水珠。这是肉中的血,汗里的盐,想抖落也抖落不掉。看看别人入这海,入那海,意气风发,斗志昂扬,也时常乱自眼来,恨从心生,恨这些劳什子的书强行让人选择一条出路玄远的生活方式。可恨到晚上,头一靠床,手就不自觉地拿起一本书,读下去,读下去,便雾失楼台,月迷津渡。

       ⑥东坡先生有喻,南人识水而不溺,北人入水则沉底。识得书性,入得字海,也算有海可入。有舟楫之便,击水之乐,狗刨几下,也淹不死,何必舍筏登岸。

       ⑦看来,那高高摞起的书还是把我砸中了,而且砸得服服贴贴,欲罢不能,这要人命的书呀!

同类题5

阅读理解

    BEIJING — China's education authority will tighten the widely criticized policy of “extra credits” for the national college entrance examination to ensure a fairer chance for all exam-takers.

    Under the policy, high school students who win awards in national Olympic competitions could get "extra credits', up to 20 points for the national college entrance exam. Students with talent in sports and students who are from ethnic groups can also benefit from this policy. The extra credits have increased these students' chances of being admitted by famous universities. Some parents were found to have helped their children fabricate(伪造)award experiences or falsify qualifications to get extra credits.

    “It has harmed education equality,” the ministry said.

    Xiong Bingqi, vice-chief of the 21st Century Education Research Institute, said the policy is designed to help students who have special talents but may be weak in academic performance to have a chance to receive higher education. It will still be needed but it is time to make the rules fairer," he said.

    The ministry said it will reduce the range of competitions whose winners can get extra credits, and limit the winners, privileges.

    The new policy will apply to students who begin high school in 2011, it said.

    Chen Lei, a mother of a 10-year-old girl, said she welcomed the ministry's policy adjustment as she does not want her daughter to become an Olympic competition geek.

    But not all the Chinese parents welcomed the new policy. “It is like a thunderbolt for me. My 13-year-old son has spent so much time studying Olympic math, and participated in so many technological competitions during vacations. It is useless now,” said Dong Wen, a 43-year-old mother.

    A student said, “Many students have changed the current study plan, and they can abandon the competition. I will be interested in learning the courses which can improve my abilities.”

    Yuan Guiren, minister of education, told China Daily that the reform is an attempt to consider the overall quality of an applicant. “But the country will not stop the national college entrance  examination as it is still the most objective way to evaluate talent in China,” he said.