[originaltext] Vitamins are essential to life. Today there are many kinds of

Vitamins are essential to life. Today there are many kinds of vitamins. A deficiency in many of these can lead to illness. (1) Vitamin A is most important for good eyesight. But it is also important for general good health. Liver contains a large amount of vitamin A, but vitamin A is also found in fish, meat, milk, butter, and in some fruits and vegetables. Vitamin B in fact consists of twelve different chemicals, which are found in eggs, cheese, butter, meal flour and vegetables. If a person does not have enough vitamin B in his diet, it may affect his whole body, particularly the skin, the nervous system and the heart. (2) Deficiency in vitamin B results in a disease called beriberi, a sort of disease in feet. Vitamin C prevents scurvy and helps to heal wounds. Some doctors believe that large quantities of vitamin C help people avoid colds. Fruits and uncooked vegetables are rich in vitamin C. A lack of vitamin C can cause a disease called scurvy. Vitamin D is essential for the growth of bones and teeth and is found in fish, liver, oil and milk. Vitamins can be produced and are sold, but (3) a well-balanced diet will provide the necessary amount of vitamins.
1. Which kind of vitamin is of primary importance to good eyesight?
2. What disease will a person suffer without vitamin B?
3. What can we learn from the passage?