问题补充:
The research is so designed that oncenothing can be done to change it.
A. begins
B. having begun
C. beginning
D. begun
答案:
A. begins
B. having begun
C. beginning
(答案→)D. begun
解析:该题题干的意思应为“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?