题干

在一定条件下,分别以高锰酸钾、氯酸钾和过氧化氢为原料制取氧气,当制得同温同压下相同体积的氧气时,三个反应中转移的电子数之比为(  )

A:1:1:1

B:4:3:2

C:2:3:1

D:2:2:1

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D

同类题1

阅读下面的文字,完成下题。

古渡头

叶紫

    太阳渐渐地隐没到树林中去了,晚霞散射着一片凌乱的光辉,映到茫无际涯的淡绿的湖上,现出各种各样的色彩来。微风波动着皱纹似的浪头,轻轻地吻着沙岸。

    破烂不堪的老渡船,横在枯杨的下面。渡夫戴着一顶尖头的斗笠,弯着腰,在那里洗刷一叶断片的船篷。

    我轻轻地踏到他的船上,他抬起头来,带血色的昏花的眼睛,望着我大声说道:“过湖吗,小伙子?”

    “唔,”我放下包袱,“是的。”

    “那么,要等到明天啰。”他又弯腰做事去了。

    “为什么呢?”我茫然地,“我多给你些钱不能吗?”

    “钱?你有多少钱呢?”他的声音来得更加响亮了,教训似的。他重新站起来,抛掉破篷子,把斗笠脱在手中,立时现出了白雪般的头发,“年纪轻轻,开口就是‘钱’,有钱就命都不要了吗?”

    我不由得暗自吃了一惊。

    他从舱里拿出一根烟管,饱饱地吸足了一口,接着说:“看你的样子也不是一个老出门的。哪里来的呀?”

    “从军队里回来。”

    “军队里?……”他又停了一停,“是当兵的吧,为什么又跑开来呢?”

    “我是请长假的。我妈病了。”

    “唔!……””

    两个人都沉默了一会儿,他把烟管在船头上磕了两磕,接着又燃第二口。

    夜色苍茫地侵袭着我们的周围,浪头荡出了微微的合拍的呼啸。我的心里偷偷地发急,不知道这老头子到底要玩什么花头。于是,我说:

    “既然不开船,老人家,就让我回到岸上去找店家吧!”

    “店家,”老头子用鼻子哼着,“年轻人到底不知事。回到岸上去还不同过湖一样的危险吗?到连头镇去还要退回七里路。唉!年轻人……就在我这船中过一宵吧。”

    他擦着一根火柴把我引到船艘后头,给了我一个两尺多宽的地方。好在天气和暖,还不至于十分受冻。

    当他再擦火柴吸上了第三口烟的时候,他的声音已经和缓多了。我躺着,一面细细地听着孤雁唳过寂静的长空,一面又留心他和我谈的一些江湖上的情形,和出门人的秘诀。

    “……就算你有钱吧,小伙子,你也不应当说出来的。这湖上有多少歹人啊!……我欢喜你这样的孝顺孩子。是的,你的妈妈一定比我还欢喜你,要是在病中看见你这样远跑回去。只是,我呢?……我,我有一个桂儿。你知道吗?我的桂儿,他比你大得多呀!你怕不认识他吧?外乡人……那个时候,我们爷儿俩同驾着这条船。我给他收了个媳妇……”

    “他们呢?”

    “他们?那一年,北佬来,你知道了吗?北佬打了败仗,从我们这里过,我的桂儿给北佬兵拉着,要他做伕子。桂儿,他不肯,脸上一拳!我,我不肯,脸上一拳!……小伙子,你做过这些个丧天良的事情吗?……

    “小伙子!你看,我等了一年,我又等了两年,三年……我的儿媳妇改嫁给卖肉的朱胡子了,我的孙子长大了。可是,我看不见我的桂儿,我的孙子他们不肯给我……他们说:‘等你有了钱,我们一定将孙子给你送回来。’可是,小伙子,我得有钱呀!

    “结冰,落雪,我得过湖;刮风,落雨,我得过湖……

    “年成荒,捐重,湖里的匪多,过湖的人少,但是,我得找钱……

     “小伙子,你是有爹妈的人,你将来也得做爹妈的。我欢喜你,要是你真的有孝心,你是有好处的,像我,我一定得死在这湖中。我没有钱,我寻不到我的桂儿,我的孙子不认识我,没有人替我做坟,没有人给我烧纸钱……我说,我没有丧过天良,可是天老爷他不向我睁开眼睛……”

    他逐渐地说得悲哀起来,终于哭了,不住地把船篷弄得呱啦呱啦地响;他的脚在船舱边下力地蹬着。可是,我寻不出来一句能够劝慰他的话,心头像给什么东西塞得紧紧的。

    外面风浪渐渐地大了起来,我翻来覆去地睡不着,他也翻来覆去地睡不着。

    可是,第二天,又是一般的微风,细雨。太阳还没有出来,他就把我叫起了。他的脸上丝毫看不出一点异样的表情来,好像昨夜间的事情,全都忘记了。

    我目不转睛的瞧着他。

    “有什么好瞧呢?小伙子!过了湖,你还要赶你的路程呀!”

    离开渡口,因为是走顺风,他就搭上橹,扯起破碎风篷来。他独自坐在船艘上,毫无表情地捋着雪白的胡子,任情地高声朗唱着:

    我住在这古渡前头六十年。  

    我不管地,也不管天,我凭良心吃饭,我靠气力赚钱!

    有钱的人我不爱,无钱的人我不怜!

    ……

    (有删改)

同类题4

阅读理解

    John Blanchard stood up from the bench, straightened his Army uniform, and studied the crowd of people making their way through Grand Central Station. He looked for the girl whose heart he knew, but whose face he didn't, the girl with the rose.

    His interest in her had begun thirteen months before in a Florida library. Taking a book off the shelf he found himself intrigued, not with the words of the book, but with the notes penciled in the margin. The soft handwriting reflected a thoughtful soul and insightful mind. In the front of the book, he discovered the previous owner's name, Miss Hollis Maynell. With time and effort he located her address. She lived in New York City. He wrote her a letter introducing himself and inviting her to correspond. The next day he was shipped overseas for service in World War II.

    During the next year and one month the two grew to know each other through the mail. Each letter was a seed falling on a fertile heart. A romance was starting Blanchard requested a photograph, but she refused. She felt that if he really cared, it wouldn't matter what she looked like.

    When the day finally came for him to return from Europe, they scheduled their first meeting —7:00 PM at the Grand Central Station in New York. “You'll recognize me,” she wrote, “by the red rose I'll be wearing on my lapel.” So at 7:00 he was in the station looking for a girl whose heart he loved, but whose face he'd never seen.

    I'll let Mr. Blanchard tell you what happened: A young woman was coming toward me, her figure long and slim. Her blonde hair lay back in curls from her delicate ears; her eyes were blue as flowers. Her lips and chin had a gentle firmness, and in her pale green suit she was like springtime come alive. I stared at her, entirely forgetting to notice that she was not wearing a rose. As I moved, a small, attractive smile curved her lips. “Going my way sailor?” she murmured.

    Almost uncontrollably I made one step closer to her, and then I saw Hollis Maynell. She was standing almost directly behind the girl. A woman well past 40, she had graying hair tucked under a worn hat. She was more than plump, her thick-ankled feet thrust into low-heeled shoes. The girl in the green suit was walking quickly away. I felt as though I was split in two, so keen was my desire to follow her, and yet so deep was my longing for the woman whose spirit had truly companioned me and upheld my own.

    And there she stood. Her pale, plump face was gentle and sensible, her gray eyes had a warm and kindly twinkle. I did not hesitate. My fingers gripped the small worn blue leather copy of the book that was to identify(识别)me to her.

    This would not be love, but it would be something precious, something perhaps even better than love, a friendship for which I had been and must ever be grateful. I squared my shoulders and saluted and held out the book to the woman, even though while I spoke I felt choked(哽咽)by the bitterness (痛苦)of my disappointment. "I'm Lieutenant (中尉)John Blanchard, and you must be Miss Maynell. I am so glad you could meet me; may I take you to dinner?"

    The woman's face broadened into a tolerant smile. "I don't know what this is about, son," she answered, "but the young lady in the green suit who just went by, she begged me to wear this rose on my coat. And she said if you were to ask me out to dinner, I should go and tell you that she is waiting for you in the big restaurant across the street. She said it was some kind of test!"

    It's not difficult to understand and admire Miss Maynell's wisdom. The true nature of a heart is seen in its response to the unattractive. "Tell me whom you love," Houssaye wrote, "And I will tell you who you are."