We get energy from the foods we eat. Our food supplies energy to keep our organs worki

ng. Our food also supplies heat to warm our bodies.

The main energy foods are the carbohydrates (碳水化合物). These are sugars and starch (淀粉). Wheat and rice are rich in starch and many fruits and vegetables contain considerable amount of sugar. Sweets, honey and jam are also rich in sugar.

Like carbohydrates, fats are food that provides us with energy. Butter, margarine, certain types of fish, eggs, cooking oils and most red meats are rich in fats. Fats can be stored in various parts of the body as reserves of energy. Because fats in general are slowly digested, they satisfy hunger for long periods.

Proteins (蛋白质) are very complex substances. The body needs proteins for the growth of new cells and for the repair and replacement of old cells. Foods rich in proteins are essential to a balanced diet. Milk, some vegetables, meat, chicken, fish, cheese, grains and nuts are some foods rich in proteins.

A good diet will contain a variety of foods so that the body contains all the minerals it needs for good health.

Vitamins are necessary for the proper working of the body. If we eat a variety of foods, we can be sure of obtaining all the vitamins we need.

Water makes up about 70 per cent of the weight of the human body. The average adult needs about two liters of water daily to replace the water the body loses.

If equal weight of the following substances is “burned” in the body, the largest amount of energy is produced by().

A、carbohydrates

B、fats

C、vitamins

D、mineral salts