单选题
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.
【答案解析】解析：空格所在句子是一个由and连接的并列句，前一个分句There are thirteen or moreof them中的them指的是vitamins，后一个分句是一个由if引导的条件状语从句，意为“如果……缺乏，(会出现)维生素缺乏症。”由于if引导的从句中谓语动词is是单数，因而，只能由一个表示单数意义的不定代词作为被选项。首先排除some，它一般用于肯定句，做主语时谓语动词用复数；其次anything与something泛指任何事或某些事，放入句中不符句意；any放入后相当于any of them，即“任何维生素”。注意any一般用于否定或疑问句中．做主语时，谓语动词常用单数，故选A。
【答案解析】解析：本题考查动词与function的搭配。四个选项中能与function搭配的只有perform，即perform a function(具有……的功能，发挥……的作用)，其他选项的常用搭配有：undertake a mission／task／project“承担使命／任务／工程”；hold a share“持有股份”；play arole／part“扮演……角色”。故选D。
【答案解析】解析：本题空格所在部分是although引导的让步状语从句。have use for是固定短语，意为“需要”，主要用于否定和疑问句中，因此，根据所在从句的含义，判断出人体对什么维生素没有营养上的需要。首先排除external和exceptional，因为不存在“外部的维生素”或“例外的维生素”；exceeding用来指被修饰的成分超出了一般的限度，它不能直接修饰“维生素”：只有excess指“超过正常或所需数额的数量”，强调“摄入过多的维生素”符合逻辑。故选C。