Prep08 174题不懂~~

yuexuannan

174.
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


请问为啥不能选C呢？笔记上解释得不是很清楚。

DUKB24

unable/able to be done is universally wrong

for it creates some self-contradictory meaning


when u say something/someone is able to do something


you imply that something/someone actually is the subject that performs such action


however，able to be done


is to convey that someone/something is  controlled to perform some actions that they can themselves perform


that makes no sense

passme

so....as to
仅用于简单的细表结构中，且结果状语的主语与主句的主语一致。

so...that
用于其它一切复杂结构， (无论结果状语的主语与主句的主语是否一致)