【正确答案】
A
【答案解析】[听力原文]
Vitamins are special chemicals that are found in foods. Although only small amounts of vitamins are needed by the human body for good health, each vitamin is extremely important. At the beginning of the twentieth century, scientists discovered that some diseases could be caused by the absence of certain kinds of food in a person"s diet. The special chemicals in these foods were called vitamins.
Vitamin A is important for the health of eyes, skin, teeth, and bones. This vitamin is found in foods such as carrots, spinach, liver, and butter. Only small amounts of vitamin A are needed by the body as large amounts can be harmful.
There are several different kinds of vitamin B and together they are often called the vitamin B complex. Vitamin B
1
helps a person feel well, and this vitamin is found in foods such as pork, peas, beans, liver, and some cereals. Vitamin B
2
helps the eyes and skin stay healthy, and is found in milk, eggs, liver, lettuce, and meat without fat. Vitamin B
6
helps the body use food better. It is present in fish, meat without fat, liver, and some cereals. Vitamin B
12
helps build healthy red blood, and it is found in liver, eggs, milk, and meat. Other kinds of the B vitamins are also important for health and are found in some of the same foods that contain vitamins B
1
, B
2
, B
6
and B
12
.
Vitamin C is another important vitamin. It keeps bones, teeth, and blood vessels strong and healthy. Some people also believe that it helps prevent colds and flu. Vitamin C is found in fresh fruits such as oranges, lemons, and grapefruits, and in vegetables such as tomatoes and cabbage.
Vitamin D helps build strong bones and for this reason it is especially important for growing children. Not many foods contain vitamin D, so it is sometimes added to milk, Sunshine also helps the body make its own vitamin D. Although the body needs vitamin D, very large amounts of it can be harmful.
Other vitamins, such as vitamin E, are being studied by scientists to find out how important they might be to good health.