2013年1月26日托福写作真题解析2013年1月26日托福写作真题解析.docVIP

2013年1月26日托福阅读真题解析 第一篇： 　　Chemistry的发展，分有机和无机。有机化学发展的慢，原因在于原材料成分太复杂，很难提纯，用非常温和的手段也会导致化学反应的发生。另一方面，研究者不知道得到的东西是不是想要的。但无机化学的原料纯度比较高，例如单质金属、硫(细节题)，故研究化学家乐于研究无机化学。 　　解析： 　　Inorganic chemistry 　　Modern chemistry, which dates more or less from the acceptance of the law of conservation of mass in the late 18th century, focused initially on those substances that were not associated with living organisms. Study of such substances, which normally have little or no carbon, constitutes the discipline of inorganic chemistry. Early work sought to identify the simple substances—namely, the elements—that are the constituents of all more complex substances. Some elements, such as gold and carbon, have been known since antiquity, and many others were discovered and studied throughout the 19th and early 20th centuries. Today, more than 100 are known. The study of such simple inorganic compounds as sodium chloride (common salt) has led to some of the fundamental concepts of modern chemistry, the law of definite proportions providing one notable example. This law states that for most pure chemical substances the constituent elements are always present in fixed proportions by mass (e.g., every 100 grams of salt contains 39.3 grams of sodium and 60.7 grams of chlorine). The crystalline form of salt, known as halite, consists of intermingled sodium and chlorine atoms, one sodium atom for each one of chlorine. Such a compound, formed solely by the combination of two elements, is known as a binary compound. Binary compounds are very common in inorganic chemistry, and they exhibit little structural variety. For this reason, the number of inorganic compounds is limited in spite of the large number of elements that may react with each other. If three or more elements are combined in a substance, the structural possibilities become greater. 　　无机化学研究始于制取常用化学品，如盐、火药等的需求。19世纪的无机化学在研究元素与常见化合物方面取得巨大成就。 　　After a period of quiescence in the early part of the 20th century, inorganic chemistry has again