英语语法问题...
All preparations (having been made), they started the experiment.
为何这里用 having been made 呢,望赐教
参考答案:1.不定式、现在分词和过去分词等前面加上自己的逻辑主语构成独立主格结构作状语时，首先要考虑它们逻辑主语的关系。存在逻辑主谓关系时，用to do,to have done,doing,having done 等,存在逻辑动宾关系时，用to be done,to have been done,done,being done,having been done等。
2.然后考虑它们与谓语在时间上的先后关系。在谓语之前的，用to have done,having done, to have been done,done等;同时的，用to do,being done,done,doing等;将来的用to do, to be done等。
本题中，having been made是现在分词making 的完成是被动式。All preparations 与 having been made是逻辑动宾关系，而且having been made发生在句子的谓语started之前。