Centuries ago, man discovered that removing moisture(潮湿)from food helps to store it, and that the easiest way to do this is to expose the food to sun and wind. In this way the North American Indians produce pemmican(dried meat ground into powder and made into cakes), the Scandinavians make stockfish and the Arabs dried dates.
All foods include water—cabbage and other leaf vegetables contains as much as 93% water, potatoes and other root vegetables 80%, lean meat 75% and fish, anything from 80% to 60%, depending on how fatty it is. If this water is removed, the activity of the bacteria(细菌)which cause food to go bad is checked.
Fruit is sun-dried in Asia Minor, Greece, Spain and other Mediterranean countries, and also in California, South Africa and Australia. Various methods are used, but in general, the fruit is spread out on trays in drying yards in the hot sun.
Nowadays most foods are dried mechanically. The method of such dehydration(脱水)is to put food in chambers through which hot air is blown at temperatures of about 110℃ at entry to about 43℃ at exit. This is the usual method for drying such things as vegetables, minced(切碎的)meat, and fish.
Dried foods take up less room and weigh less than the same food packed in cans or frozen, and they do not need to be stored in special conditions. For these reasons they are invaluable to the climbers, explorers and soldiers in battle, who have little storage space. They are also popular with housewives because it takes so little time to cook them. Usually it is just a case of replacing the dried-out moisture with boiling water.
According to the text, the open-air method of drying food      .

A．is the one most commonly used today

B．was invented by the American Indians

C．has been known for hundreds of years

D．tends to be unhealthy

Bacteria which cause food to go bad       .

A．cannot live in sunlight

B．are killed by drying

C．are in no way dependent on the water contained

D．have their activity greatly reduced by drying

Today vegetables are most commonly dried        .

A．on hot and sunny days	B．in hot-air chambers
C．in the sun and wind	D．using the open tray method

Housewives like dried foods because they        .

A．are quick to prepare

B．taste better than fresh foods

C．can be packed in a case

D．look fresh when cooked