关于enough偏向主观判断

wrr1230

Often major economic shifts are so gradual as to be indistinguishable at first from ordinary fluctuations in the financial markets.
A. so gradual as to be indistinguishable
B. so gradual so that they can be indistinguishable
C. so gradual that they are unable to be distinguished
D. gradual enough not to be distinguishable
E. gradual enough so that one cannot distinguish them
这是prep08语法笔记里的，D选项的解释是
D.    enough偏向于主观判断，不符合逻辑语境；not to be distinguishable不如to be indistinguishable简洁

什么叫偏向主观判断？
还有我看到曼哈顿的中文精简版里有一条是unaccompanied是不好的表达，意思不如not accompanied 清晰，但是为什么这里
是not to be distinguishable不如to be indistinguishable简洁？

kwok1123

关于enough这个不会。第二点提醒楼主， not accompanied 是动词形式， unaccompanied是形容词，gmat偏向动词，表达更清晰。 但是distinguishable 和 indistinguishable都是形容词。

wrr1230

明白了，谢谢~