Vitamins are organic compounds necessary in small amounts in the diet for the normal growth and maintenance of life of animals,i

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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 transforming foods into energy and body maintenance.There are thirteen or more of them,and if【C2】______is missing a deficiency disease becomes【C3】______.
    Vitamins are similar because they are made of the same elements—usually carbon, hydrogen, oxygen, and sometimes nitrogen.They are different【C4】______their elements are arranged differently,and each vitamin【C5】______one or more specific functions in the body.
    【C6】______enough vitamins is essential to life,【C7】______the body has no nutritional use for【C8】______vitamins.Many people,【C9】______,believe in being on the "safe side" and thus take extra vitamins.However,a【C10】______diet will usually meet all the body’s vitamin needs.
【C7】

选项 A、although
B、and
C、yet
D、both

答案A

解析 Although意为“尽管”。其余三个词意思不对。
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