填空题 　　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, ---|||________|||--- do they construct or build part of the body. They are needed for ---|||________|||--- foods into energy and body maintenance. There are thirteen or more of them, and if ---|||________|||--- is missing a deficiency disease becomes ---|||________|||--- . 　　Vitamins are similar because they are made of the same elements―usually carbon, hydrogen, oxygen, and ---|||________|||--- nitrogen. They are different ---|||________|||--- their elements are arranged differently, and each vitamin ---|||________|||--- one or more specific functions in the body. 　　 ---|||________|||--- enough vitamins is essential to life, although the body has no nutritional use for ---|||________|||--- vitamins. M people, ---|||________|||--- , 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.