Asteroids are different forms of the meteoroids that race across the night sky. Most orbits the sun far from Earth and don't threaten us. But there are also thousands of asteroids whose orbits put them on a violent coming course together with Earth.
Buy $ 50 million worth of new telescopes right now. Then spend $10 mil]ion a year for the next 25 years to locate most of the space rocks. By the time we spot a fatal one, the scientists say, we'll have a way to change its course.
Some scientists favor pushing asteroids off course with nuclear weapons. But the cost wouldn't be cheap.
Is it worth it? Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think asteroids big enough to destroy lots of life might strike Earth once every 500,000 years. Sounds pretty rare but if one did fall it would be the end of the world. "If we don't take care of these big asteroids, they'll take care of us. "Says one scientist. "Its that simple."
The cure, though, might be worse than the disease, Do we really want fleets of nuclear weapons silting around on Earth? "The world has less to fear from doomsday rocks than from a great nuclear fleet set against them. "Said a New York Times article.
What does the passage say about asteroids and meteoroids?
A.They are heavenly bodies similar in nature.
B.There are more asteroids than meteoroids.
C.They are heavenly bodies different in composition.
D.Asteroids are more mysterious than meteoroids.
What is e-books' negative impact on social relationships?
A.They create new jobs only for writers.
B.Fewer and fewer people have access to new technology.
C.They may threaten some traditional trades.
D.They isolate people from one another.
A.except for
B.beside
C.except
D.besides
A.facts, opinions
B.opinions, facts
C.written, unwritten rules
D.verbal, nonverbal
The tomato is originally an American plant. It was found in South America by early Spanish explorers. The word tomato comes from the native Nahuatl word tomatl. But when it moved north, the plant earned a different name. Remarkably, the settlers in North America thought it was poisonous. They believed that to eat it was surely to die. It was said that deserted suitors would threaten to eat a tomato to cause their coldhearted lovers-regret. Because of this legend, the settlers called the tomato a "love apple." While people enjoyed other native plants such as corn and sweet potatoes, everyone avoided the tomato.
No one knows who first dared to eat a tomato. Perhaps someone was brave enough, or lovesick enough, to try out the truth of the rumors. Of course, whoever ate this fruit was perfectly safe. No one died from eating a love apple. Still, it was many years before the people fully believed that the tomato was a safe, and even good food. But its use did become common, and the plant was sent across the ocean to become part of many traditional European dishes.
The language from which we derived the word tomato is______.
A.Portuguese
B.Spanish
C.Nahuati
D.European
A.Because
B.If
C.Although
D.Whether
A. whom
B. which
C. that
D. them
A.outlook (观点)
B.outnumber
C.outflow
A.tested
B.examined
C.traced
D.rolled