题干

某化合物由两种元素组成,它在空气中完全燃烧时,只生成水和二氧化碳。根据质量守恒定律,该化合物(    )  

A:由氮元素和氢元素组成

B:由碳元素和氧元素组成

C:由氢元素和氧元素组成

D:由碳元素和氢元素组成

上一题 下一题 0.0难度 选择题 更新时间:2018-02-25 12:03:42

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D

同类题1

阅读理解

    You have probably been told by your high school instructor that writing is an important and practical skill. However, you may not be convinced that the ability to write will be important in your own future. If so, you will be surprised at the results of a recent survey by the National Institute of Education. More than four thousand working men and women who had graduated fifteen years earlier were asked to name the courses they would have taken in college if they had known better. The designer of the survey expected people to name courses in computer science, mathematics, or business. But the course most often mentioned was writing.

    If you already have a job, you are probably not surprised at their answers. Many jobs require the ability to write. Despite the increasing use of the telephone and the computer, much information must be communicated in writing.Some ten million people—managers, engineers, sales representatives, and many others— write regularly as part of their jobs. Summaries, reports, reports, letters and speeches are required in today's work world. The ability to write, therefore, is an important skill. The successful individual is almost always the one who can communicate successfully in writing.

    Writing communicates your thoughts and feelings to others; it also tells you something about yourself. Maybe this is what Eldridge Cleaver had in mind in his autobiography, “I started to write... to save myself...I had to seek out the truth... I had to find out who I am and what I want to be ,what type of man I should be ,and what I could do to become the best of which I was capable.”

同类题3

阅读《白梅无价》,完成下列各题。

白梅无价

韩静霆

    ①当代大画家李苦禅撒手人寰驾鹤西游的时候,我的老师许麟庐正在山东旅行。许老听到噩耗,立即登车,直奔北京。到了苦禅灵堂,满头白发的老人,长跪不起,恸哭不止。他和苦老,同是齐白石大师的弟子,手足之情,比一奶同胞还亲。师兄师弟,年轻时在白石先生左右,一个是左膀,一个是右臂。贫困的时候,他们一个烧饼掰作两半儿充饥。艺术上更是志趣相投,画画儿画疯了的时候,两个人一夜之间画一刀纸,一百张,酣畅淋漓。这会儿苦禅一去不归,许老恨不能跟随而去。那哭声,真是撕心裂肺,好几个年轻人才把他从灵前拉起来。透过老人迸溅的泪花,我能感受到两位画家半生坎坷、相濡以沫的深厚情感,感受到这种渗透着深深文化气息的友谊是何其珍贵。

    ②第二天,许老到我家来,进门就说:“静霆啊,苦禅兄走了啊……”接着又嚎啕起来,这回是在“家”里哭,而且当着我和我妻子的面儿。许老失去了大师兄,那种绝望的悲伤,那种真情的倾泻,让我永生永世都忘不掉。

    ③那天,妻子做了老师爱吃的饼,弄了几样好菜,还有好酒,可老师吃不下饭去,看许老骨瘦形销的样子,我们执意请他休息一会儿,睡个午觉。谁知,许老刚躺下,又爬起来,大叫“拿宣纸来”。我那时经济不大宽裕,哪里有好宣纸存用?翻箱倒柜,才找到两张质量低劣的四尺宣纸,两只破毛笔。许老捉了笔就在四尺宣纸上横扫。他哪里是在作画,简直是要划破阴阳之界。他笔笔中锋,含泪挥笔画梅花。只听见宣纸沙沙地响,力透纸背,情透纸背。毛笔直冲斜行,犹如剑器在许老手中挥舞。他把痛悼师兄之情,倾洒在纸上,朵朵梅花都是泪!老师画枝干的时候,一言未发,该点蕊了,说了四个字“泥里拔钉”。梅蕊虽“拔”了出来,可他却无法从情感中自拔。

    ④这张四尺宣纸上的白梅花,干湿浓淡,墨色淋漓,疏影横斜,笔意纵横。笔墨狂放霸气,不仅世间难得如此珍品,就连许老自己也绝对不可能再画出第二张。就像人不可能诞生两次一样,这幅佳作不能克隆,不可重复,甚至不能临摹。那个年代,那个下午,许老那种横扫千军的运笔速度,那种大悲大恸之后,寻觅到的恣意渲泻情感的方式,也绝对没有第二回。

    ⑤那天,许老收了笔,兀自对着那张白梅看了好半天。我大气也不敢出。心里痒,想要这幅画儿,可是不敢说。沉吟半晌,许老说:“带上,到我家盖上章子,给你了。”我张着嘴喘气,不知道说什么好。

    ⑥白梅,已经成为我的传家之宝。只有在夜深人静的时候,我和妻子才会小心翼翼地把这张画儿展开,来一番精神享受。我不敢拿到裱画店里去裱褙,怕裱坏了。仔细想想,许老的这幅画昭示了一个道理:在中国画界,松竹兰梅笔情墨意,难免重复,可至珍至宝的神品,不是百无聊赖时的遣兴,也不是文人的笔墨游戏,而是在笔端凝注了浓烈的情感,集人生和艺术的体验,在某个特别的时间创作的东西。正因为如此,神在,许老的白梅在。开卷总有一股真气扑面,那种感觉,常常是唯见神采不见梅花。那些神来之笔,甚至画家自己也始料不及。

    ⑦我记得白石老人曾赠给许老一幅画,上面题了一行字,大意是:是许姓好子孙,当宝之。许老没有在这幅白梅上题这些字,可我会珍藏好的。因为,白梅无价。

(有删改)