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【单选题】
The researchers wished to compare the six soil samples collected during experiments 1 and 2 according to permeability (ability of water to pass through them). A portion of each sample was placed in a separate cup with a filter bottom, and then the same amount of water was added to each cup. After one minute, the amount of water passing through each filter was measured. In order to draw any reliable conclusions about the permeability of the six original samples, all of the following conditions are necessary EXCEPT:A.
one minute is sufficient time for some amount of water to escape at least some of the cups.
B.
the same amount of soil was added to all six cups.
C.
in each cup, the proportions of sand, silt, and clay were the same as in the original sample.
D.
the filters did not allow soil particles to escape through the bottoms of the cups.
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