[单项选择]

Africa is the second largest continent in the world, Yet much of Africa has not been developed by man into farms and cities. One of the reasons is that a dangerous and unpleasant insect called the tsetse fly(采采蝇)is found there. This fly makes its home in the heart of Africa.
The tsetse fly is a little larger than the housefly. Its name means "fly that destroys cattle". It lives by sucking blood from animals. It attacks man, as well as his herds of cattle.
The tsetse fly carries sleeping sickness to those men it bites. Sleeping sickness makes men veryill, and some forms of it cause death. The tsetse fly also causes diseases in animals. In some places in Africa, it has destroyed whole cattle herds.
It is hard for man and his cattle to live with the tsetse fly. Some experts even think that it has kept 400 million square miles of Africa a wilderness. This wilderness is a place as large as the whole United States. Without the tsetse fly, more land cou
A. People have done nothing to get rid of the tsetse flies.
B. People are trying to find out ways to get rid of the tsetse flies.
C. No ways can be found to get rid of the tsetse flies.
D. It won’t be long before people get rid of all the tsetse flies in Africa.

[单项选择]

Africa is the second largest continent in the world, Yet much of Africa has not been developed by man into farms and cities. One of the reasons is that a dangerous and unpleasant insect called the tsetse fly(采采蝇)is found there. This fly makes its home in the heart of Africa.
The tsetse fly is a little larger than the housefly. Its name means "fly that destroys cattle". It lives by sucking blood from animals. It attacks man, as well as his herds of cattle.
The tsetse fly carries sleeping sickness to those men it bites. Sleeping sickness makes men veryill, and some forms of it cause death. The tsetse fly also causes diseases in animals. In some places in Africa, it has destroyed whole cattle herds.
It is hard for man and his cattle to live with the tsetse fly. Some experts even think that it has kept 400 million square miles of Africa a wilderness. This wilderness is a place as large as the whole United States. Without the tsetse fly, more land cou
A. the second largest continent in the world
B. a dangerous and unpleasant insect
C. farmland in the heart of Africa
D. a kind of illness that can destroy cattle

[单项选择]The world’s smallest continent and sixth largest country by total area, Australia-owing to its size and isolation-is often dubbed the "______", and is sometimes considered the world’s largest island.
A. island continent
B. lost continent
C. Noah’s Ark
D. Lost Paradise

[单项选择]1 In the second half of the 20th century, the world became, quite literally, a darker place.
2 Defying expectation and easy explanation, hundreds of instruments around the world recorded a drop in sunshine reaching the surface of Earth, as much as 10 percent from the late 1950’s to the early 90’s, or 2 percent to 3percent a decade. In some regions like Asia, the United States and Europe, the drop was even steeper. In Hong Kong, sunlight decreased 37 percent.
3 No one is predicting that it may soon be night all day, and some scientists theorize that the skies have brightened in the last decade as the suspected cause of global dimming, air pollution, clears up in many parts of the world.
4 Yet the dimming trend — noticed by a handful of scientists 20 years ago but dismissed then as unbelievable — is attracting wide attention.
5 "There could be a big gorilla sitting on the dining table, and we didn’t know about it," said Dr. Veerabhadran Ramanathan, a professor of climate and
A. motivations
B. powers
C. courses
D. causes

[单项选择]

Canada is the second largest country in the world in area, although its (21) is only some 25 million, most (22) in a 200-mile strip (23) the southern border. Over 25 percent of the (24) number live in the three main cities. The northern areas of the country are almost uninhabited (25) for isolated settlements.
Canada is (26) a rich country, and its national (27) per capita is the fifth highest in the world, but its economy in recent years has been rather (28) , because of the varied nature of what it does.
Over the last three years, the Canadian economy has been hard (29) by failing oil prices and by rising US interest (30) . This has (31) to a steep fall in industrial production-by as much as a fifth since 1981. Some (32) now think Canada is on the (33) to recovery, though more cautions spirits say that no (34) can be expected until there is
A. jobs 
B. founds 
C. rates 
D. industries