[单项选择]If the radius of a circular region were decreased by 20 percent, the area of the circular region would decrease by what percent
A. 16%
B. 20%
C. 36%
D. 40%
E. 44%

[单项选择]If the radius of a circular region were decreased by 20 percent, the area of the circular region would decrease by what percent
A. 16%
B. 20%
C. 36%
D. 40%
E. 44%

[填空题]Bear populations have decreased because humans have overhunted hears and occupied their habitat.

[填空题]Profits decreased steadily throughout the three year period.

[填空题]Bicycle sales decreased steadily from 1998 to 2000

[单项选择]The market value of a certain machine decreased by 30 percent of its purchase price each year. If the machine was purchased in 1982 for its market value of $8,000, what was its market value two years later ？（）
A. $8，000
B. $5，600
C. $3，200
D. $2，400
E. $800

[单项选择]The population decreased from the 1840s until about 1970s, largely because of （　）.
A. a low birth rate
B. a high death rate
C. a low employment rate
D. a high emigration rate

[填空题]Weight loss and decreased appetite are signs and symptoms of summer SAD.

[单项选择]Auto crashes have decreased in recent years, but the number of deaths in crashes still averages around 40,000 every year. A much higher number of crashes result in permanent disability. Because car crashes are usually caused by human errors, it is always necessary to remind drivers of the following safety tips:
Avoid distractions—Safe driving takes concentration. If a driver is talking on a mobile phone, the driver is not paying enough attention to the road. Distracted driving is a factor in 25 to 30 percent of all traffic crashes.
Take extra care in wild weather—Sometimes, bad weather conditions will contribute to an accident by interfering with visibility or making it difficult to keep the car under control. A driver always should take the effects of the weather, such as strong winds or slippery roads, into consideration when driving.
Avoid sleepiness—Sleepy driving causes more than 100,000 crashes each year, resulting in 40,000 injuries and 1,550 deaths on aver
A. there is a rise in the number of auto crashes in recent years
B. the number of people who died in auto crashes has increased
C. 40,000 auto crashes cause permanent disability each year
D. auto accident death rate has remained high in recent years

[单项选择]The large size and roughly circular shape of the Pacific made some scientists think that it （） a hole left when the moon separated from the earth.
A. used to be
B. would have been
C. might have been
D. should have been