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

题型：不详难度：来源：

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

A．begins	B．having begun
C．beginning	D．begun

答案

D

解析

该题题***意思应为“研究工作计划得如此周密,一旦工作开始,什么事情也改变不了它”｡当once (或when, while, if, as if, though/although, as, until, until, whether, unless, since等)引导状语从句时,若从句中的主语与主句中的主语相同(或从句中的主语为it), 且从句的谓语中有be时,可省略从句中的主语和be, 而只保留形容词､分词､动词不定式､介词短语等,故答案为D｡