21. Bubbles， flaws， and other irregularities diffuse the light that passes through stained glass， _________ the glass sparkle.
A. which making
B. and making
C. making
D. to making
答案：C
分析：空格前的句子结构完整，这里的分词作状语。A中用which来引导非限制性定语从句，而句中无谓语，错；B中and作为连接词，而and后的句子不完整，没有谓语，错；D错，不定式的结构应该是to do.
参考译文：气泡，裂纹和其他的不规则会使光线穿过受损的玻璃时发散开，使得玻璃闪闪发光。
补充： stained glass常指教堂的彩色玻璃
22. Fog is common near ________ _ inland bodies of water and along coasts in temperate zones.
A. there are large
B. large
C. either large
D. where large
答案：B
分析：A使得句中出现两个谓语动词，且中间无连接词，错；C应该是either… or…结构，但句中没有出现or；D中where引导的句子不完整，错。
参考译文：雾通常在靠近大型内陆水体和沿着温和地带边缘的地方发生。
23. The portrayal of everyday life in the objects of folk art makes it _________ valuable source of history.
A. and a
B. so that a
C. a
D. is a
答案：C
分析：make结构，make+n.1/pron+n.2/adj.
参考译文：描述日常生活的民间艺术品使它们本身成为有价值的历史来源。
24. _______ by the United States government's Bureau of Labor Statistics， the Consumer Price Index compares current costs of goods and services with past costs.
A. To prepare
B. As it prepared
C. When preparation
D. Prepared
答案：D
分析：由后半句可以知道句子的逻辑主语应该是Consumer Price Index， 而且空格后是by，所以应该用被动形式，只能选D.
参考译文：消费者价格索引是美国政府劳工统计部完成的，它把现在的物品价格跟以前的做了比较。
25. _________ carries the genes， which determine the hereditary characteristics of the cell or organism.
A. The chromosome
B. The chromosome that
C. Whereas the chromosome
D. There is a chromosome
答案：A
分析：该句是非限制性定语从句，前半句已经有谓语和宾语，缺主语，选A.
参考译文：染色体携带了遗传物质，这些遗传物质决定了细胞和生物体的遗传特性。
26. _________ directly with most metals to form compounds called carbides.
A. Carbon reacting
B. Carbon reacts
C. The reaction of carbon
D. When carbon reacts
答案：B
分析：从句意来看，called在这里不是谓语动词，而是分词做后置定语：…… which are called carbides.空格中缺主语和谓语，选B.
参考译文：碳直接跟大部分金属反应而形成碳化物的化合物。
27. Meteorites are slowed down by Earth's atmosphere， but if they are moving _________， they can form a crater on impact.
A.

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