单选题Directions: For each blank in the following
passage, choose the best answer from the choices given below. Mark your answer
on the Answer Sheet by drawing with a pencil a short bar across the
corresponding letter in the brackets. 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, {{U}} {{U}} 1 {{/U}} {{/U}}do they construct or
build any part of the body. They are needed for {{U}} {{U}} 2
{{/U}} {{/U}}foods into energy and body maintenance. There are thirteen or
more of them, and if {{U}} {{U}} 3 {{/U}} {{/U}}is missing a
deficiency disease becomes, {{U}} {{U}} 4 {{/U}}
{{/U}} Vitamins are similar because they are made of the same
elements—usually carbon, hydrogen, oxygen, and {{U}} {{U}} 5
{{/U}} {{/U}}nitrogen. They are different {{U}} {{U}} 6
{{/U}} {{/U}}their elements are arranged differently, and each vitamin
{{U}} {{U}} 7 {{/U}} {{/U}}one or more specific functions in the
body. {{U}} {{U}} 8 {{/U}} {{/U}}enough
vitamins is essential to life, although the body has no nutritional use for
{{U}} {{U}} 9 {{/U}} {{/U}}vitamins. Many people, {{U}}
{{U}} 10 {{/U}} {{/U}}, 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.