[填空题]Tens and thousands of years passed before wheels were used to make a vehicle.

[单项选择]

Sleep

For millions of years before the appearance of the electric light, shift work, all-night cable TV and the Internet, Earth’s creatures evolved on a planet with predictable and reassuring 24-hour rhythms. Our biological clocks are set for this daily cycle. Simply put, our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives. (Contrary to popular belief, humans don’t need less sleep as they age.)
But in average, Americans sleep only about seven and a half hours per night, a marked drop from the nine hours they averaged in 1910. What’s worse, nearly one third of all Americans get less than six hours of sleep on a typical work night. For most people, that’s not nearly enough.
Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep
A. Most people need less sleep when they grow older.
B. Most people need seven and a half hours of sleep every night.
C. On average, people in the U. S today sleep less per night than they used to.
D. For most people, less than six hours of sleep on a typical work night is enough.

[单项选择]But cellphones had been around for 15 years before they caught on with（　） America. By that yardstick, broadband-widely available for only the past couple of years-has many more miles to go.
A. main-topmast
B. mainstay
C. main artery
D. mainstream

[单项选择]

Thousands of years before Columbus came to the New World, the American Indians entered North America by crossing a narrow strip of land that once connected Alaska and Siberia. The migrants entered a new world in which there were no people at all. But there were many animals to hunt, and there were forests where nuts, roots and berries could be gathered.
(27) When the Europeans came to the New World, the Indians, at first, taught the settlers how to plant corn, bake fish, make canoes and smoke tobacco. In return, the whites introduced horses, guns, gun-powder and alcohol. But at last, there were struggles for land, and the struggles could have only one result-war. When the wars were over, all Indians were moved to large tracts of land called reservations. Now, some of them, embittered by past mistreatment, are determined to preserve their tribal life; some wish to modernize the reservations. These alternatives, with many variations, are what most Indians have chosen
A. with Columbus
B. before Columbus did
C. after Columbus’ arrival
D. in the 18^th century

[单项选择]Exactly three years before the year in which Anna was born, the year was 1980 x. In terms of x, on Anna’s twentieth birthday, the year will be ？（）
A. 1977+x
B. 1997+x
C. 2003-x
D. 2003+x
E. 2006+x

[单项选择]For millions of years before the appearance of the electric light, shift work, all-night cable TV and the Internet, Earth’ s creatures evolved on a planet with predictable and reassuring 24 - hour rhythms. Our biological clocks are set for this daily cycle. Simply put, our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives. ( Contrary to popular belief, humans don’ t need less sleep as they age. )
But on average, Americans sleep only about seven and a half hours per night, a marked drop from the nine hours day averaged in 1910. what’s worse ,nearly one third of all Americans get less than six hours of sleep on a typical Work night. For most people, that’ s not nearly enough.
Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep disorders. Some sleeping disorders are generic. But ma
A. Staying up late.
B. Taking a hot bath.
C. Having late meals.
D. Traveling between time zones.