题干

洗发产品中含有的枸橼酸(C6H8O7)能使头发柔顺有弹性且气味清香。下列关于枸橼酸的说法正确的是(   )

A:枸橼酸由6个碳原子、8个氢原子和7个氧原子构成

B:枸橼酸属于有机高分子化合物

C:枸橼酸中氧元素的质量分数最大

D:枸橼酸中碳、氢、氧三种元素的质量比为 6:8:7

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答案(点此获取答案解析)

C

同类题1

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                                                                                                        我为白菜狂的日子
                                                                                                                   莫 言
        12岁那年,一个临近春节的早晨,母亲叹息着,并不时把目光抬高,瞥一眼那三棵吊在墙上的白菜。最后,母亲的目光锁定在白菜上,端详着,终于下了决心似的,叫我去找个篓子来。“娘”我悲伤地问,“您要把它们……”“今天是大集。”母亲沉重地说。“可是,您答应过的,这是我们留着过年的……”话没说完,我的眼泪就涌了出来。“我们种了一百零四棵白菜,卖了一百零一棵,只剩下这三棵了……说好了留着过年包饺子的……”我哽咽着说。母亲靠近我,掀起衣襟,擦去了我脸上的泪水。透过矇眬的泪眼,我看到母亲把那两棵较大的白菜从墙上摘下来。最后,那棵最小的、形状圆圆像个和尚头的也脱离了木橛子,挤进了篓子里。我熟悉这棵白菜,因为它生长在最靠近路边那行的拐角处,小时被牛踩了一脚,一直长得不旺。我和母亲格外关照它。尽管还是小,但卷得十分饱满,收获时母亲拍打着它,感慨地对我说:“你看看它,你看看它……”在那一瞬间,母亲脸上洋溢着欣喜的表情,仿佛拍打着一个历经磨难终于长大成人的孩子。
         去集市的路上,寒风凛冽,有太阳,很弱,仿佛随时都要熄灭似的。我的手很快冻麻了,篓子跌在地上,篓底有几根蜡条跌断了,那棵最小的白菜从篓子里跳出来,滚到路边结着白冰的水沟里,根跌损了。母亲在我头上打了一巴掌,然后小心又匆忙地下到沟底将它抱上来放进篓子。我知道闯了大祸,哭着说:“我不是故意的,我真的不是故意的……”母亲的脸色缓和了,没再打骂我,只用一种温暖的腔调说:“不中用,把饭吃到哪里去了?”然后蹲下身,将背篓的木棍搭上肩头。
         终于挨到了集上,母亲将篓子放在七姥爷的旁边,就让我去上学。我也想走,但看到一个老太太朝着我们的白菜走了过来。她用细而沙哑的嗓音问了白菜的价钱,摇摇头,看样子是嫌贵。但她没有走,而是蹲下,揭开那张破羊皮,翻动着我们的三棵白菜。她把那棵最小的白菜上那半截欲断未断的根拽了下来,然后又用枯柴一样的手指,逐棵地戳着我们的白菜。撇着嘴说我们的白菜卷得不紧。母亲用忧伤的声音说:“大婶子啊,这样的白菜您还嫌卷得不紧,那您就到市上,看看哪里还能找到卷得更紧的?”
         我对这个老太太充满了恶感,你拽断了我们的白菜根也就罢了,可你不该昧着良心说我们的白菜卷得不紧。我忍不住冒出了一句话:“再紧就成了石头蛋子了!”老太太惊讶地看着我。母亲转回头批评我:“小小孩儿,说话没大没小的!”老太太撕扯着那棵最小的白菜上那层已干枯的菜帮子。我十分恼火,便刺她:“别撕了,你撕了让我们怎么卖?!”“你这个小孩子,说话怎么就像吃了枪药一样呢?”老太太嘟哝着,但撕扯菜帮子的手却并不停止。她终于还是将那层干菜帮子全部撕光,露出了鲜嫩、洁白的菜帮。这样的白菜包成饺子,味道该有多么鲜美啊!老太太抱着白菜站起来,让母亲给她过秤。终于核准了重量,老太太说:“俺可是不会算账。”
         母亲因偏头痛,算了也没算清,对我说:“社斗,你算。”我找了根草棒,用刚学的乘法,在地上算着。我报了一个数字,母亲跟着报出。“没算错吧?”老太太用不信任的目光盯着我说。“你自己算就是了。”我说。“这孩子,说话真是暴躁。”老太太低声嘟哝着,从腰里摸出一个肮脏的手绢,层层揭开,露出一沓纸票,沾了些唾沫,一张张地数着。她终于将数好的钱交到母亲的手里。我看到七姥爷尖锐的目光在我脸上戳了一下,然后移开。
        我放了学回家,一进屋就看到母亲正坐在灶前发呆。三棵白菜都躺在蜡条篓子里,那棵最小的因剥去了干帮子,已经受了严重的冻伤。我的心猛地一沉,知道最坏的事情已经发生了。母亲抬起头,眼睛红红地看着我,许久,用一种让我终生难忘的声音说:“孩子,你怎么能这样呢?你怎么能多算人家一毛钱呢?”“娘”我哭着说,“我……”“你今天让娘丢了脸……”母亲说着,两行泪挂在了腮上。这是我看到坚强的母亲第一次流泪,至今想起,心中依然沉痛。                            

同类题5

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    The uninvolved dad, turning up his nose at diapering(换尿布) and too busy to bathe, dress and play with his kids, is mostly a myth(神话) , a big government survey suggests. Most American fathers say they are heavily involved in hands-on parenting, the researchers found.

    The results are encouraging and important " because others have found the more involved dads  are, the better the outcomes for their children. " said researcher Jo Jones of the National Center for Health Statistics, part of the Centers for Disease Control Prevention. She co-authored the report released Friday.

    "Times have changed," said Robert Loftus, 34, of Yonkers, NY. He quit a six-figure sales job a year ago to care for his two young children while his wife works full time. "We are trying to rethink our priorities (优先考虑的事) and family seem to be NO.1 priority while in the past maybe people were more focused on career. "

    The study involved nearly 4.000 fathers who were interviewed in person between 2009 and 2013.

◇ Key findings among fathers living with children younger than 5 :

*9 in 10 bathed, diapered, helped them use the toilet or get dressed at least several times weekly .

* Even higher numbers played with them and ate meals with them that often

* Almost 2 0ut of 3 read to them at least several times weekly.

◇Among dads living with kids aged 5-18.

* More than 9 0ut of 10 ate meals with them at least several times weekly and talked with them about what happened during the kids' day that often.

* Almost 2 0ut of 3 helped with homework several times weekly.

* About half took their kids to or from activities that often.

    Dr. David Hill, a Wilmington, N. C. pediatrician (儿科医生) said the survey reflects what he's seen among his patients' fathers. Increasingly, fathers rather than mothers take their kids to the doctor. Some "are anxious about changing a diaper, " he said.

    Census(调查) numbers show that there were almost 190,000 stay-at-home dads nationwide last year versus 93,000 in 2010. Loftus, the New York stay-at-home dad, said, "I feel fortunate to be able to be such a hands-on father.  I'm doing the most significant occupation in the world. "