The research is so designed that once________nothing can be done to change it.

A. begins B. having begun

C. beginning D. begun

D


解析:

該題題干的意思應(yīng)為“研究工作計(jì)劃得如此周密,一旦工作開始,什么事情也改變不了它”｡當(dāng)once (或when, while, if, as if, though/although, as, until, until, whether, unless, since等)引導(dǎo)狀語(yǔ)從句時(shí),若從句中的主語(yǔ)與主句中的主語(yǔ)相同(或從句中的主語(yǔ)為it), 且從句的謂語(yǔ)中有be時(shí),可省略從句中的主語(yǔ)和be, 而只保留形容詞､分詞､動(dòng)詞不定式､介詞短語(yǔ)等,故答案為D｡

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