The plan is heard _____ so well that we don't need to make any change.

问题描述:

The plan is heard _____ so well that we don't need to make any change.
A designed B to be designed
为什么不用B

designed过去分词表示计划已经设计好了
而B中to be designed表示将要被设计,从后面可以看出明显方案已经设计好了