[单项选择]Scientists have been puzzled for decades by how turtles manage to navigate across the Atlantic — but now they know. The creatures have their own inbuilt magnetic compass.
A laboratory experiment has revealed that the tiny turtles are born with the ability to "detect" the magnetic fields which help them to navigate the 8,000 miles across the stormy Atlantic Ocean and back home again.
After hatching from eggs laid in nests along beaches in Florida, baby turtles swim out into this current and flow with it for years, nudged along by warm waters rich in food.
They seem to use both the intensity and direction of the magnetic field to navigate. It is also found that turtles born in the Pacific are genetically imprinted with a different magnetic map for currents from those in the Atlantic. They would soon perish in the Atlantic.
It can be inferred that ______.
A. turtles navigate with a compass
B. turtles only make use of the direction of the magnetic field
C. turtles will eventually go back to the place where they are born
D. scientists have different opinions as to how turtles make their way home

[单项选择]Scientists have been puzzled for decades by how turtles manage to navigate across the Atlantic — but now they know. The creatures have their own inbuilt magnetic compass.
A laboratory experiment has revealed that the tiny turtles are born with the ability to "detect" the magnetic fields which help them to navigate the 8,000 miles across the stormy Atlantic Ocean and back home again.
After hatching from eggs laid in nests along beaches in Florida, baby turtles swim out into this current and flow with it for years, nudged along by warm waters rich in food.
They seem to use both the intensity and direction of the magnetic field to navigate. It is also found that turtles born in the Pacific are genetically imprinted with a different magnetic map for currents from those in the Atlantic. They would soon perish in the Atlantic.
Scientists didn’t know decades of years ago that ______.
A. turtles have their own inbuilt magnetic compass
B. what kind of compass is built in turtles’ body
C. what kind of map turtles use in navigating
D. why turtles don’t die in the Atlantic

[简答题]For the last four decades, who have been more vulnerable(易受影响的)to unemployment

[单项选择]Decades of（）might have been partially responsible for our ignorance of development abroad.
A. insulation
B. irrigation
C. integration
D. isolation

[单项选择]Attempts have been made for nearly three decades to increase the amount of precipitation from clouds by seeding them with salt or silver iodide.（　）
A. Devices
B. Hypotheses
C. Efforts
D. Suggestions

[单项选择]

How many people have been to the moon
A. 20.
B. 16.
C. 2.
D. 12.

[单项选择]How many libraries have been established with the money donated by Andrew Carnegie（　）.
A. 500.
B. 1500.
C. 2500.
D. 3500.

[单项选择]How many people worldwide have been infected with HIV since the start of the epidemic
A. 47 million.
B. 4 billion.
C. 25 million.
D. 44 million.

[单项选择]For more than two decades, U.S. courts have been limiting affirmative-action programs in universities and other areas. The legal rationale is that racial preferences are unconstitutional, even those intended to compensate for racism or intolerance. For many colleges, this means students can be admitted only on merit, not on their race or ethnicity. It has been a divisive issue across the U. S., as educators blame the prolonged reaction to affirmative-action for declines in minority admissions. Meanwhile, activists continue to battle race preferences in courts from Michigan to North Carolina.
Now chief executives of about two dozen companies have decided to plunge headfirst into this politically unsettled debate. They, together with 36 universities and 7 non-profitable organizations, formed a forum that set forth an action plan essentially designed to help colleges circumvent court-imposed restrictions on affirmative action. The CEOs’ motive: "Our audience is growing more diverse,
A. think it wrong to deprive the minorities of their rights to receive education.
B. want to conserve the fine characteristics of American nation.
C. want a workforce that reflects the diversity of their customers.
D. think it their duty to help develop education of the country.