单项选择题 'My own feelings went from disbelief to excitement to downright fear', says Carl Hergenrother, 23, an Arizona undergraduate who verified a large asteroid barreling toward Earth with a 230cm telescope atop nearby Kitt Peak. 'It was scary, because there was the possibility that we were confirming the demise of some city somewhere, or some state or small country'. Well, not quite. Early last week, his celestial interloper whizzed by Earth, missing the planet by 450,620 km—a hairbreadth in astronomical terms. Perhaps half a kilometer across, it was the largest object ever observed to pass that close to Earth. Duncan Steel, an Australian astronomer, has calculated that if the asteroid had struck Earth, it would have hit at some 93460 km/h. The resulting explosion, scientists estimate, would have been in the 3000-to-12000-megaton range. That says astronomer Eugene Shoemaker, a pioneer asteroid and comet hunter, 'is like taking all of the U.S. and Soviet nuclear weapons, putting them in one pile and blowing them all up'. And what if one of them is found to be on a collision course with Earth? Scientists at the national laboratories at Livermore, California, and Los Alamos, New Mexico, have devised a number of ingenious plans that, given enough warning time, could protect Earth from a threatening NEO. Their defensive weapons of choice include long distance missiles with conventional or, more likely, nuclear warheads that could be used either to nudge an asteroid into a safe orbit or blast it to smithereens. Many people including some astronomers—are understandably nervous about putting a standby squadron of nuclear tipped missiles in place. Hence the latest strategy, which in some cases would obviate the need for a nuclear defense: propelling a fusillade of cannonball-size steel spheres at an approaching asteroid. In a high-velocity encounter with a speeding NEO, explains Gregory Canavan, a senior scientist at Los Alamos, 'the kinetic energy of the balls, would change into heat energy and blow the thing apart'. Some astronomers oppose any immediate defensive preparations, citing the high costs and low odds of a large object's striking Earth in the coming decades. But at the very least, Shoemaker contends, NEO detection should be accelerated. 'There's this thing called the 'giggle factor' in Congress', he says. 'people in Congress and also at the top level in NASA still don't take it seriously. But we should move ahead. It's a matter of prudence'. The world, however, still seems largely unconcerned with the danger posed by large bodies hurtling in from space, despite the spectacle two years ago of Comet Shoemaker-Levy 9 riddling the planet Jupiter with mammoth explosions. It remains to be seen whether last week's record near-miss has changed any minds.From the first three paragraphs, we learn thatA．the earth narrowly escaped a catastrophe.B．one asteroid almost destroyed an entire city.C．asteroids are comparable to nuclear weapons.D．the planet earth is vulnerable to dangers.

单项选择题 Analysts have their go at humor, and I have read some of this interpretative literature, (1)_____ without being greatly instructed. Humor can be (2)_____, (3)_____ a frog can, but the thing dies in the process and the innards are (4)_____ to any but the pure scientific mind. One of the things (5)_____ said about humorists is that they are really very sad people-clowns with a breaking heart. There is some truth in it, but it is badly (6)_____. It would be more (7)_____, I think, to say that there is a deep vein of melancholy running through everyone's life and that the humorist, perhaps more (8)_____ of it than some others, compensates for it actively and (9)_____. Humorists fatten on troubles. They have always made trouble (10)_____. They struggle along with a good will and endure pain (11)_____, knowing how well it will (12)_____ them in the sweet by and by. You find them wrestling with foreign languages, fighting folding ironing boards and swollen drainpipes, suffering the terrible(13)_____ of tight boots. They pour out their sorrows profitably, in a (14)_____ of what is not quite fiction nor quite fact either. Beneath the sparking surface of these dilemmas flows the strong (15)_____ of human woe. Practically everyone is a manic depressive of sorts, with his up moments and his down moments, and you certainly don't have to be a humorist to (16)_____ the sadness of situation and mood. But there is often a rather fine line between laughing and crying, and if a humorous piece of writing brings a person to the point (17)_____ his emotional responses are untrustworthy and seem likely to break over into the opposite realm, it is (18)_____ humor, like poetry, has an extra content, it plays (19)_____ to the big hot fire which is Truth, and sometimes the reader feels the (20)_____.A．whileB．althoughC．butD．if

单项选择题 AMERICA'S central bank sent a clear message this week. For the second consecutive meeting, the Federal Open Market Committee, the central bank's policy-making committee, left short term interest rates unchanged at 1.75%. But it said that the risks facing the economy had shifted from economic weakness to a balance between weakness and excessive growth. This shift surprised no one. But it has convinced many people that interest rates are set to rise again—and soon. Judging by prices in futures markets, investors are betting that short-term interest rates could start rising as early as May, and will be 1.25 percentage points higher by the end of the year. That may be excessive. Economists at Goldman Sachs, who long argued that the central bank would do nothing this year, now expect short-term rates to go up only 0.75% this year, starting in June. But virtually everyone reckons some Fed tightening is in the offing. The reason? After an unprecedented 11 rate-cuts in 2001, short term interest rates are abnormally low. As the signs of robust recovery multiply, analysts expect the Fed to take back some of the rate-cuts it used as an 'insurance policy' after the September 11th terrorist attack. They think there will be a gradual move from the Fed's current 'accommodative' monetary stance to a more neutral policy. And a neutral policy, many argue, ultimately implies short term interest rates of around 4%. Logical enough. But higher rates could still be further off, particularly if the recovery proves less robust than many hope. Certainly, recent economic indicators have been extraordinarily strong: unemployment fell for the second consecutive month in February and industrial production rose in both January and February. The manufacturing sector is growing after 18 months of decline. The most optimistic Wall Streeters now expect GDP to have expanded by between 5% and 6% on an annual basis in the first quarter. But one strong quarter does not imply a sustainable recovery. In the short term, the bounce-back is being driven by a dramatic restocking of inventories. But it can be sustained only if corporate investment recovers and consumer spending stays buoyant. With plenty of slack capacity around and many firms stuck with huge debts and lousy profits, it is hard to see where surging investment will come from. And, despite falling unemployment, America's consumers could disappoint the bulls. These uncertainties alone suggest the central bank will be cautious about raising interest rates. Indeed, given the huge pressure on corporate profits, the Federal Reserve might be happy to see consumer prices rise slightly. In short, while Wall Street frets about when and how much interest rates will go up. The answer may well be not soon and not much.The purpose of the author in writing this text is toA．interpret the message from the central bank,B．justify the rise of short term interest rates.C．illustrate what is weakness and undue growth.D．contrast different views on economic indices.