精選閱讀詞匯筆記（三）

精選閱讀詞匯筆記（三）

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P7

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic "rays"are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it: in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one- minute point that helium could exist. By this time, the universe had cooled sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formation of helium went on for only a relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

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elements : n. 原理,基礎
helium : n. 氦
quantity : n. 量,數量,總數
accurate : a. 正確的,精確的
abundance : n. 豐富,充足,大量
galaxy : n. 銀河,星系,一群顯赫的人物
relatively : ad. 相對地
interstellar : a. 星際的
quasar : n. 恒星狀球體,半星球體,類星球體
nuclei : n. nucleus 的復數形nucleus : n. 核心,核子,原子核,中堅
constituent : n. 成分,選民,構成物;a. 構成的,組織的,有選舉權的
radiation : n. 放射線
consist : vi. 組成,存在,一致
particle : n. 粒子,點,極小量
ratio : n. 比,比率
convert : n. 皈依者,改變宗教者;vt. 使改變信仰,轉換,兌換,倒置;vi. 皈依
responsible : a. 有責任的,負責的,責任重大的,可靠的
manner : n. 樣子,禮貌,風格
significant : a. 重要的,有效的,有含義的,暗示的,非偶然的
consequently : ad. 結果
indicate : vt. 指出,顯示,象征,指示
particle : n. 粒子,點,極小量
sufficient : a. 充分的,足夠的
neutron : n. 中子
proton : n. 質子
stick : n. 棍,棒,刺,莖,枯枝,條狀物;vt. 插于,刺入,釘住,使停止,伸出,粘貼;vi. 粘住,停留,堅持,陷住,伸出
effectively : ad. 有效地,有力地,實際上
cease : n. 停止;vi. vt. 停止,終了

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P8

Are organically grown foods the best food choices?The advantages claimed for such foods over conventionally grown and marketed food products are now being debated. Advocates of organic foods ----- a term whose meaning varies greatly --- frequently proclaim that such products are safer and more nutritious than others.

The growing interest of consumers in the safety and nutritional quality of the typical North American diet is a welcome development. However, much of this interest has been sparked by sweeping claims that the food supply is unsafe or inadequate in meeting nutritional needs. Although most of these claims are not supported by scientific evidence, the preponderance of written material advancing such claims makes it difficult for the general public to separate fact from fiction. As a result, claims that eating a diet consisting entirely of organically grown foods prevents or cures disease or provides other benefits to health have become widely publicized and form the basis for folklore.

Almost daily the public is besieged by claims for "no-aging" diets, new vitamins, and other wonder foods. There are numerous unsubstantiated reports that natural vitamins are superior to synthetic ones, that fertilized eggs are nutritionally superior to unfertilized eggs, that untreated grains are better than fumigated grains, and the like.

One thing that most organically grown food products seem to have in common is that they cost more than conventionally grown foods. But in many cases consumers are mislead if they believe organic foods can maintain health and provide better nutritional quality than conventionally grown foods. So there is real cause for concern if consumers, particularly those with limited incomes,distrust the regular food supply and buy only expensive organic foods instead.

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organically : ad. 有機性地,器官上地,有組織地
choice : n. 選擇,精選品,選擇權;a. 精選的,挑三揀四的,可選的
advantage : n. 優點,便利,好處,優勢;vt. 有助于