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题库 / Prep2007E1-SC-23
While they remove carbon dioxide from the air, conserve soil and water, and house thousands of species, forests also supply potentially valuable pharmaceuticals, and, as sources of building material and firewood, that provide employment for millions worldwide.
pharmaceuticals, and, as sources of building material and firewood, that provide
pharmaceuticals, and sources of building material and firewood, are providers of
pharmaceuticals and, as sources of building material and firewood that are providing
pharmaceuticals and sources of building material and firewood, for providing
pharmaceuticals and, as sources of building material and firewood, provide
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DE 区别：
D：森林还提供具有潜在价值的药品以及建筑材料和薪柴来源，以为全球数百万人提供就业机会。
E: 森林还提供具有潜在价值的药品，并且作为建筑材料和薪柴的来源，为全球数百万人提供了就业机会。
药材不能提供就业机会，只有作为“source” 才能提供就业机会
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