Read the following passage and write the letter A, B, C or D on your answer sheet indicate the correct answer to each of the questions from 28 to 32. Not so many years ago, the word vitamin was known only to a few scientists. Today i used, and the importance of vitamins in our foods is common knowledge. Vitamins are life-giving substances found in foods and are needed for the proper growth and general health of the body. The different kinds of vitamins are indicated by letters of the alphabet. ...

Read the following passage and write the letter A, B, C or D on your answer sheet indicate the correct answer to each of the questions from 28 to 32.

Not so many years ago, the word vitamin was known only to a few scientists. Today i used, and the importance of vitamins in our foods is common knowledge. Vitamins are life-giving substances found in foods and are needed for the proper growth and general health of the body. The different kinds of vitamins are indicated by letters of the alphabet. At the present time, vitamins A, B1, B2, C, D and E are known. A proper diet should contain a collection of foods in which all of these vitamins are present. Vitamins are also prepared and sold in tablet and capsule form.

Each vitamin has its particular work to do in the life-giving process. Vitamin B1, for example, benefits appetite and digestion. It also helps the body grow. Another vitamin helps the blood to clot, so that danger of bleeding to death in case of injury is lessened. Still another makes the eyes stronger of seeing at night. Airplane pilots need plenty of this vitamin. Scientists think vitamins may have some effects on keeping the hair from turning gray.

What is the main idea of the passage?