To help preserve ancient Egyptian monuments threatened by high water tables, a Swedish engineering firm has proposed installing pumps, perhaps solar powered, to lower the underground water level and dig trenches around the bases of the stone walls.
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Ato lower the underground water level and dig trenches
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Bto lower the underground water level and to dig trenches
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Cto lower the underground water level and digging trenches
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Dthat lower the underground water level and that trenches be dug
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Ethat lower the underground water level and trench digging
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显示答案
正确答案: C