GWD-TN-19

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第39题
After increasing steadily for centuries, the total annual catch of all wild fish peaked in 1989; since that time, the total catch for most species has declined or plateaued, prompting conservation efforts designed to help prevent population crashes and possible extinctions.

B.    fish peaked in 1989; since that time, the total catch for most species has declined or plateaued, prompting
C.    fish peaked in 1989, but with the total catch since then declining or plateauing in the case of most species, prompting
D.    fish had peaked in 1989; since that time, the decline or plateau of the total catch for most species, which prompted
E.    fish, which peaked in 1989, and, in the case of most species, it has declined or plateaued since, prompted
F.    fish, which peaked in 1989 but has since declined or plateaued for most species, and this prompted

这道题我选了E，答案是A，我想问的是到底什么时候用分词啊，这里为什么要用prompting啊。解释下啊