Vitamins are organic compounds necessary in small amounts in the diet for th

游客2025-04-03 21

问题 Vitamins are organic compounds necessary in small amounts in the diet for the normal growth and maintenance of life of animals, including man.
They do not provide energy, 【C1】______do they construct or build any part of the body. They are needed for【C2】______foods into energy and body maintenance. There are thirteen or more of them, and if 【C3】______is missing a deficiency disease becomes【C4】______.
Vitamins are similar because they are made of the same elements—usually carbon, hydrogen, oxygen, and【C5】______nitrogen. They are different【C6】______their elements are arranged differently, and each vitamin【C7】______one or more specific functions in the body.
【C8】______enough vitamins is essential to life, although the body has no nutritional use for 【C9】______vitamins. Many people, 【C10】______, believe in being on the "safe side" and thus take extra vitamins. However, a well balanced diet will usually meet all the body’s vitamin needs. [br] 【C5】

选项 A、mostly
B、partially
C、sometimes
D、rarely

答案 C

解析本句破折号后举例说明维生素的组成成分：碳、氢、氧和______氮，and表明各成分之间为并列关系，选项应与usually相呼应。usually是频度副词，选项也应是频度副词。mostly和partially不是频率副词，而是强调事物部分与整体的关系，rarely是频率副词，但它含否定含义，若用于句中，之前的连词and应改为表示转折关系的but。故选C。

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