To what extent will future scientific discoveries____the prolonging of human life?A.be made possible B.make possibleC.make it possible D.be made it possible

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選A 由于future scientific discoveries是主語，該句應(yīng)用被動語態(tài)，且句子已有賓語，句子前后協(xié)調(diào)。

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C. 其中it為形式賓語

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B future scientific discoveries主語