問題詳情
2
(A) encompassed
(B) artifact
(C) umbrage
(D) granulated
(E) fluke(AB) exorbitantly (AC) prepossessing (AD) ensuing (AE) vanishingly (BC) debunked(BD) zapped (BE) minuscule (CD) entailing (CE) caveat (DE) moniker
Astronomers were pretty sure they’d long since solved the mystery of how the Moon was born. It was an open question untilApollo astronauts started in the late 1960’s. In the mid-1970s, scientists successfully (36) the myth: billions of years ago,something the size of Mars smacked into the Earth, creating a Moon’s worth of molten debris that quickly cooled, moved into astable orbit and became our familiar cosmic companion. Over the (37) decades, however, it became clear that Houston had a problem. The lunar samples were similar to thoseon Earth. The two kinds of rock should have shown at least minor differences, reflecting the unique chemical makeup of the longgoneMars-size cannonball known by its common (38) , Theia. But no matter how hard geochemists looked, they couldn’tfind any. Theorists devised a number of ways around the dilemma, most of them (39) much more complicated collisionscenarios. However, as planetary scientist Robin Canup said, “Every time you add an extra complication, you reduce the overallprobability of an event happening.” You could keep your collision theory, in short, but only by assuming that the whole episode was an utter (40) , soimprobable that it shouldn't have happened at all — exactly the kind of wild scenario that scientists winced at. But a study justpublished in Science may have set things right. The chemical composition of Moon and Earth rocks, says lead author DanielHewartz, of the University of Gottingen, turns out not to be so similar after all — close, but not identical. “The difference wefound is very slight,” he says. “It’s so small that previous studies couldn’t detect it.” Hewartz’s analysis did detect it by concentrating on an abundance of oxygen-17, a rare version of the element that has nineneutrons in its atoms rather than the usual eight. “Our study shows that the moon has just a bit more O-17 than Earth,” Hewartzexplains. “Just a bit” meaning a(n) (41) .012 percent more, but that’s enough. “This means that Theia had slightly more aswell.” Hewartz and his colleagues were able to spot such (42) small amounts of oxygen-17 thanks to a new technique theydevised. They first sealed the lunar rocks in a chamber filled with fluorine gas and then (43) the sample with a laser tovaporize a tiny bit of it. The scientists then drained out gas plus vapor and sent it through a chromatograph, which separated freeoxygen liberated from the rock from the other gases. Not only did the team see elevated O-17 in samples NASA provided them; they also saw it in samples other groups hadalready looked at without finding anything. That, says Canup, “tends to support their claim.” The only (44) , she warns, isthat the difference they detect between Earth and the Moon is so small that there’s likely to be a debate over whether they’reseeing something real, or whether it’s simply a(n) (45) of the way they interpret their raw data.
【題組】36
參考答案
答案：B,C
難度：困難0.272727
統計：A(2),B(15),C(12),D(3),E(0)