Question

The research is so designed that once ________ nothing can be done to change it.

A．begins

B．having begun

C．beginnings

D．begun

 

Answer 1

答案：D
解析：

对本题设空之前once一词用法的判断是做出正确选择的关键： once(或者其他连词如when，while，since等)引导状语从句时，如果从句主语与主句主语一致，可以省略其中的主语和be动词谓语结构，例如： Once in bed, the children usually stay there. (=Once they are in bed, the children usually stay there.) When finished, the building will be opened by the Prince of Wales. (=When it is finished, the building will be opened by the Prince of Wales.) While at college (=While she was at college), Delia wrote a novel. 本题所给句子的句意为： The research is so designed that once it (=the research)is begun nothing can be done to change it．也就是： ...once begun nothing can be done to change it．

提示：