53. The word“stimulated”can be replaced by “______”.

A. protected　　　　 B. encouraged　 　　　　 C. enabled　　 　　　　 D. persuaded

52. What does the passage mainly discuss?

A. Causes of food going bad.　　　　 　　　　　　　　　　 B. Production of iceboxes.

C. Inventions that led to changes in food and drink.　 D. Canned food.

51. Ever-growing rabbits ______.

A. were an only supply of skins for the poor to change for cash

B. were a disaster for humans to balance nature

C. can only be controlled by chemical methods

D. didn't draw the Commonwealth government's attention

E

Before the mid-nineteenth century, people in the United States ate most foods only in season. Drying, smoking, and salting could keep meat for a short time, but the chance of eating fresh meat and drinking fresh milk was very limited; there was no way to keep food from going bad. But in 1810 a French inventor named Nicolas Appert developed the cooking-and-sealing technique of canning. And in the 1850's an American named Gall Borden developed a means of keeping milk fresh. Canned foods and condensed milk (炼乳) became more common during the 1860's, but supplies remained low because cans had to be made by hand. By 1880, however, inventors had developed modern machines that mass-produced cans from tinplate. Suddenly all kinds of food could be kept and bought at all times of the year.

Other inventions had also helped make it possible for Americans to change their daily diets. Growing populations increased food demand and stimulated fruit and vegetable farmers to raise more produce. Railroad refrigerator cars made it possible to ship fruits and packed meat fresh to faraway places without worrying they would go bad. Thus, by the 1890's northern city settlers could enjoy southern and western strawberries, grapes, and tomatoes, for a month at most in the past, for up to six months of the year. Besides, increased use of iceboxes made it possible for families to store food which could easily go bad. An easy means of producing ice had been invented in the 1870's, and by 1900 the nation had more than two thousand ice plants, most of which made home deliveries. The icebox became common equipment in most homes and remained so until the refrigerator replaced it in the 1920's and 1930's. Almost everyone now has a variety of diet.

50. In the 1930s Depression years, Which is NOT mentioned?

A. poorer Australians could afford to buy rifles to kill rabbits

B. wealthy Australians disliked rabbits deeply

C. most kids experienced rabbit-hunting for meals

D. the rich land-holder also sold rabbit skins for money

49. Rabbits moved ________.

A. more slowly in open country than in woods

B. in woods as fast as in open country

C. much faster in open country than in woods

D. slowly in woods as well as in open country

48. During the 1930s Depression, in Australia, rabbits _______.

A. were food for hungry people　 　　　　　　 B. ate up huge areas of grazing land

C. were killed for fun　　　　　　　　 　　　 D. made grass-eating animals starve

47. Finger-prints have often been used as a method of solving criminal case because it ______.

A. is complicated but reliable　 　　　　　　　　　 B. is simple and not expensive

C. is expensive but easy to do　 　　　　　　　　　 D. can bring a lot of money

­D

Biological Invasion (入侵): Rabbits, an Australian Way of Life .When introduced to Australia, rabbits proved a disaster. The story is from multiple sides-from how rabbits destroyed vast zones of grazing land (畜牧场), to what natives thought, to the 1930s Depression (大萧条) when rabbits kept hungry stomachs full.

Rabbits, even with human help, took some six centuries to spread throughout Britain. They spread faster than any introduced mammal (哺乳动物) anywhere. They moved 10 to 15 kilometres a year through forests and up to 130 kilometres across open country.

Rabbits ate seedlings until no plants remained left. Grazing animals starved. Pasture and soil disappeared. After 1880, many rabbit-control methods were tried but nothing worked.

Rabbits reached central Australia in 1894. T. Tjupurrula tells how his father saw one of the first rabbits in Pintupi country, Northern Territory, in 1908:“That yumpita's had gone into a hole. Might be dangerous one. Look-out! : Nose, whiskers big one eyes, long one ears: Alright, he's not dangerous one, he's only eating grass.”

Big landowners hated rabbits. Yet many small farmers and poorer Australians, both European and natives, needed them. For the price of a cheap rifle or a few steel traps, they had an endless supply of meat for their families and skins to sell for cash. Many a kid of the Depression years remembers creeping out into the forest to trap rabbits for breakfast. Just 30 years after rabbits were introduced, governments were offering a small fortune for a way of finishing them. Many methods of rabbit control failed. Instead, Australians learned to keep out further species that might run wild. From 1940 onwards, the Commonwealth (联邦) Scientific and Industrial Research Organisation (CSIRO) experimented with chemical and biological methods of rabbit control. Fumigation (烟熏法) seemed promising, but under pressure from land-holders, CSIRO used myxomatosis (多发性粘液瘤). It spread rapidly, killing millions of rabbits.

46. Some criminals remove their own finger-prints by ______.

A. using printer's ink　　　　　 　　　　　　　　　 B. injuring the inner skin

C. damaging the outer skin　　 　　　　　　　　　 D. damaging the colour

45. If your fingers are wounded by knife, fire or other means, the structure of skin will _____.

A. be changed partly　　　　　　 　　　　　　　 B. be replaced by a different one

C. be the same when the wound is recovered　 D. become ugly

44. Scientists and experts have proved that the pattern of a human being's finger skin____.

A. is similar to his mother's　　　　　

B. is valuable to himself only

C. is like that of others with the same type of blood

D. is different from that of all others