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When Neil Armstrong and Buzz Aldrin returned from the moon, their cargo included nearly fifty pounds of rock and soil, which were packed in an aluminum box with seals designed to maintain the lunar surfaces low-pressure environment. But back at Johnson Space Center, in Houston, scientists discovered that the seals had been【C1】______—by moon dust. Lunar dust is fine, like a powder,【C2】______it cuts like glass. Its formed when shooting stars【C3】______on the moons surface, heating its rocks and dirt and reducing them to fine particles. Since theres no wind or water to smooth【C4】______edges, the tiny grains are sharp and uneven, and【C5】______nearly everything. 'The intruding【C6】______of lunar dust represents a more challenging engineering design issue, as well as a【C7】______issue for settlers, than does radiation,' wrote Harrison Schmitt, an Apollo 17 astronaut, in his 2006 book, 'Return to the Moon.' The dust damaged space-suits and ate away layers of moon boots. Over the【C8】______of six Apollo missions, not one rock box【C9】______its vacuum seal. Dust followed the astronauts back into their ships, too. According to Schmitt, it smelled like gunpowder and made breathing【C10】______. No one knows precisely what the extremely small particles do to human lungs. The dust not only【C11】______the moons surface, but floats up to sixty miles【C12】______it—as an outer part of its atmosphere, where particles【C13】______the moon by gravity, but are so thin that they【C14】______collide. In the nineteen-sixties, Surveyor probes filmed a glowing cloud floating just above the lunar surface during sunrise. Later, Apollo 17 astronaut Gene Cernan, while orbiting the moon, recorded a【C15】______phenomenon at the sharp line where lunar day meets night. Cernan【C16】______a series of pictures illustrating the changing【C17】______; streams of particles popped【C18】______the ground and hovered, and the resulting cloud came into sharper focus as the astronauts orbiter approached daylight. Since theres no wind to form. and【C19】______the clouds, their origin is something of a mystery. Its【C20】______that theyre made of dust, but no one fully understands how or why they do their thing.
【C1】
A.destroyed
B.stained
C.changed
D.consolidated

A.'
B.
【C1】
A.destroyed
B.stained
C.changed
D.consolidated


【参考答案】

A
上句提到从月球上带回来的石块和泥土是放置在一个特制密封的铝盒里,能保持类似月球表面的低压环境(low-pressureenvironment)。从本句的But推断,这个密封装置可能出现了问题,下段提到月尘非常锋利(itcutslikeglass)。因此A项destroyed“被破坏”符合......

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未分类题【C3】

未分类题The happier you are, the better, right? Not necessarily. Studies show that there is a darker side to feeling good and that the【C1】______of happiness can sometimes make you less happy. Too much cheerfulness can make you deceivable, less successful—and thats only the tip of the iceberg. Happiness does have【C2】______. It can protect us from stroke and from the common cold, makes us more【C3】______to pain and even【C4】______our lives. Yet, June Gruber, a psychologist warns that its important to experience positive moods in moderation. She compares happiness to food:【C5】______necessary and beneficial, too much food can cause problems;【C6】______, happiness can lead to bad outcomes. 'Research indicates that very high levels of positive feelings【C7】______risk-taking behaviors, excess alcohol and drug consumption, overeating, and may lead us to【C8】______threats,' she says. How else can excessive joy, or having lots of positive emotions and a relative absence of【C9】______ones, hurt you? First, it may【C10】______your career prospects. Psychologist Edward Diener, known for his happiness research, and his colleagues analyzed a variety of studies, and discovered that those who early in their lives reported the highest life【C11】______years later reported lower income than those who felt slightly less【C12】______when young. Whats more, they【C13】______school earlier. Included in the studies was one【C14】______a group of American college freshmen who in 1976 claimed to be very cheerful. Surveyed again when they were in their late 30s, they earned, on average, almost $3,500 a year less than their slightly less cheerful【C15】______. Why? Diener suggests that people who dont experience much sadness or anxiety are【C16】______dissatisfied with their jobs and therefore feel less pressure to get more education or change careers. Psychologists point out that emotions are【C17】______: They make us change behavior. to help us【C18】______. Anger prepares us to fight; fear helps us flee. But what about sadness? Studies show that when we are sad, we think in a more systematic manner. Sad people are attentive【C19】______details and externally oriented, while happy people【C20】______make snap judgments that may reflect racial or sex stereotyping.【C1】A.absenceB.pursuitC.claimD.illusion