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  3. The tower of Pisa has been leaning so long—nearly 840 years—that it’s natural to assume it will go against gravity forever. But

The tower of Pisa has been leaning so long—nearly 840 years—that it’s natural to assume it will go against gravity forever. But

admin2022-07-18  43
问题     The tower of Pisa has been leaning so long—nearly 840 years—that it’s natural to assume it will go against gravity forever. But the famous structure has been in danger of collapsing almost since its first brick was laid.
    It began leaning shortly after construction began in 1173. Builders had only reached the third of the tower’s planned eight stories when its foundation began to settle unevenly on soft soil composed of mud, sand and clay. As a result, the structure leaned slightly to the north. Laborers tried to compensate by making the columns and arches of the third story on the sinking northern side slightly taller. They then proceeded to the fourth story, only to find themselves out of work when political unrest halted construction.
    The tower sat unfinished for nearly 100 years, but it wasn’t done moving. By the time work restarted in 1272, the tower tilted to the south—the direction it still leans today. Engineers tried to make another adjustment, this time in the fifth story, only to have their work interrupted once again in 1278 with just seven stories completed.
    Unfortunately, the building continued to settle, sometimes at an alarming rate. Finally, between 1360 and 1370, workers finished the project, once again trying to correct the lean by angling the eighth story, with its bell room, northward.
    In 1989, a similarly constructed bell tower in Pavia, northern Italy, collapsed suddenly. Officials became so worried the tower of Pisa would suffer a fate similar to the collapsed tower in Pavia that they closed the monument to the public. A year later, they rallied together an international team to see if the tower could be brought back from the brink.
    By 2001, the team had decreased the tower’s lean by 44 centimeters (17 inches), enough to make officials confident that they could reopen the monument to the public. The actions taken by Burland and his team could, theoretically, stabilize the structure forever. The real threat now comes from the masonry (石造建筑) itself, especially the material in the lower stories, where most of the forces caused by the centuries-long leaning have been directed. If any of this masonry crushed, the tower could collapse. And even a minor earthquake in the region could have devastating consequences.
    In spite of these potential problems, engineers expect the famous structure will remain stable for at least another 200 years. By then, another intervention may be required, but the technology available to make improvements could be far more advanced and preserve the tower for another 800 years.
Why does the real threat come from the tower itself?
选项 A、Because it was too old after so many years.
B、Because people think it is out of fashion.
C、Because years’ stress is on the material in the lower stories.
D、Because someone damaged it intentionally.
答案C
解析 细节题。根据题干中的the real threat可定位到原文第六段第三句，该句提到，真正的威胁来源于塔本身，特别是较低楼层，因为几个世纪来倾斜造成的压力都集中于此。由此可知，C选项符合，故选C。
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