【题目】The decision ________, what is to be done now is how to carry it out.
A.is made
B.has been made
C.having been made
D.having made

【答案】C
【解析】题干中逗号前缺少状语，根据题干前后整体看，空白处不可能为句子，the decision与make之间是被动关系，the decision having been made符合句意。句意：决定已经做出，我们现在所要做的就是如何实施它。故答案选C。