【单选题】

Questions 47 to 56 are based on the following passage.

Before refrigerators, homes usually had ice boxes.But (47) way to keep food cool without the need for electricity is to use an evaporative cooler. This is easy to make and does not even use (48) .
A、common design is a tall box with food placed on several shelves inside. The shelves are pieces of metal with many small holes through them. The sides of the box are (49) with pieces of thick cloth.Containers of 50) axe placed at the top and bottom of the cooler. The ends of each piece of cloth lie in the water so the cloth stays wet.
Put the cooler in the open air but not in the sun. (51) will pass through the wet cloth. The inside of the box will (52) several degrees cooler than the outside air temperature.And this may be (53) enough to keep foods fresh at least for a short time.
Cold (54) in a freezer, however, can keep foods in good condition fox months after the (55) season. Yet foods can be damaged if they are kept too cold TheBritish development group PracticalAction says the best way to prepare foods for storage is at (56) time while still in the fielD、Use a sharp knife to avoid damage.
A、stayI) covered
B、storageJ) under
C、harvestK) water
D、other L) cold
E、growingM) air
F) anotherN) preparation
G) iceO) take
H) cool