阅读以下文字,完成以下问题。 人们在夏季出门时,大多担心会患皮肤癌,所以夏天要买高防晒值的防晒霜、防晒服、遮阳伞,很多国家的操场上还盖上了遮阳篷。 事实上,太阳光对人体健康非常有利,且必不可少,人体中维生素D(VD)的一部分获取就应归功于太阳光。人体一是通过食用鱼油、乳制品等食物获取,二是皮肤细胞利用致癌的紫外线把前体化学物转化成VD,经肝脏和肾脏进一步合成活性VD。 活性VD最广为人知的作用是帮助肠道吸收钙。钙不仅用于连接骨细胞,在神经、肌肉和新陈代谢指令中也具有非常重要的作用。当血钙浓度下降,血液就会从骨骼中提取钙,以防止神经和肌肉失灵,这就是为什么缺VD容易患软骨症。但钙的新陈代谢并不是VD的惟一作用。最新研究表明活性VD对抑制细胞分裂有重要作用。如果缺乏VD,细胞分裂就会失控,而细胞分裂失控会毫无疑问地导致癌症。美国科学家在对美国各地癌症死亡率的图表分析时惊讶地发现,很多常见癌症包括结肠癌、乳腺癌和前列腺癌在东北部地区的死亡率明显高于其他地区,而东北部地区寒冷,阳光照射强度和时间都不及南方各地。因此科学家提出,在户外活动时间长、接受光照较多的人,阳光为他们的皮肤中制造了更多的有防癌作用的VD。科学家分析比较了癌症死亡率图表与各地区的紫外线照射强度,数据显示、紫外线强度与13种癌症的死亡率有很大关联。科学家的结论是,美国每年至少有23600人因缺少阳光或光照不足而患癌死亡。 英国一个研究小组记录了355名男性一生的日照时间后发现,他们中1/4接触阳光最少的人与1/4接触阳光最多的相比,前者患癌症的几率是后者的3倍。 目前人们流行服用维生素,但这一领域的有关专家认为,服用一颗以上的多种维生素是不可行的,因为药丸中的其他维生素,特别是VA,很快会达到有害剂量,而单纯服用VD,过量摄入也是有害的。但你永远不可能摄入过量的阳光,因为皮肤制造VD,本身就有防止VD过量的反馈途径。 研究还指出,接触阳光还有一些好处是无法靠服用维生素获得的。皮肤细胞利用紫外线还可制造其他化学物质如光甾醇,速甾醇等,这些甾醇被认为对人健康有益,此外,紫外线有温和的消毒杀菌作用,可以杀死人体皮肤的一些病毒和细菌,阳光中有催眠因子,能调节人体生物节律,阳光能为人体提供合理健康因子,这些都是服药无法达到的。 综上所述,强烈的太阳光虽然会使皮肤变黑,影响皮肤的细嫩美观,但合理、适宜的晒太阳对人体生理健康,心情舒畅是大有益处的。 活性VD的作用说法不正确的一项是( )。
A. 抑制细胞分裂
B. 缺少它会导致肠癌、乳腺癌等癌症
C. 防止神经失灵
D. 防止患软骨症
一、数字推理每题给你一个数列,但其中缺少一项,要求你仔细观察数列的排列规律综合判断,然后从四个供选择的选项中,选出最恰当的一项,来填补缺项。 84,64,47,33,( ),14
A. 12
B. 14
C. 22
D. 24
Directions: There are 4 reading passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C, and D. You should decide on the best choice and mark your answer on the ANSWER SHEET by blackening the corresponding letter in the brackets. The single business of Henry Thoreau, during forty-odd years of eager activity, was to discover all economy calculated to provide a satisfying life. His one concern, which gave to his ramblings in Concord fields a value of high adventure, was to explore the true meaning of wealth. As he understood the problems of economics, there were three possible solutions open to him, to exploit himself, to exploit his fellows, or to reduce the problem to its lowest denominator. The first was quite impossible--to imprison oneself in a treadmill when the morning called to great adventure. To exploit one’s fellows seemed to Thoreau’s sensitive social conscience an even greater infidelity. Freedom with abstinence seemed to him better than serfdom with material well-being, and he was content to move to Walden Pond and set about the high business of living, "to front only the essential facts of life and to see what it had to teach." He did not advocate that other men should build cabins and live isolated. He had no wish to dogmatize concernig the best mode of living--each must settle that for himself. But that a satisfying life should be lived, he was virtually concerned. The story of his emancipation from the lower economics is the one romance of his life, and Walden is his great book. It is a book in praise of life rather than of Nature, a record of calculating economies that studied saving in order to spend more largely. But it is a book of social criticism as well, in spite of its explicit denial of such a purpose. In considering the true nature of economy he concluded, with Ruskin, that the cost of a thing is the amount of life which is required in exchange for it, immediatey or in the long run. In Walden Thoreau elaborated the text: "The only wealth is life." In Thoreau’s opinion, the price of a thing should be measured in terms of ______.
A. pleasure
B. effort
C. money
D. life