多项选择题
For Questions 16 through 20, select the two answer choices that, when used to complete the sentence, fit the meaning of the sentence as a whole and produce completed sentences that are alike in meaning.
The （） of sediment in the river caused concern among environmentalists and industrialists alike; the water levels in the river were being reduced almost daily.
A. accretion
B. disposal
C. depletion
D. alienation
E. ethnology
F. accumulation