关于so as to 用法的两个官方题目矛盾，求斑竹赐教

happyself

这题是OG12 的37题，根据og解释so x as to y是不符合习惯用法的：
37. Although schistosomiasis is not often fatal, it is so
debilitating that it has become an economic drain on
many developing countries.
(A) it is so debilitating that it has become an
economic
(B) it is of such debilitation, it has become an
economical
(C) so debilitating is it as to become an economic
(D) such is its debilitation, it becomes an
economical
(E) there is so much debilitation that it has become
an economical
Idiom
? is sentence correctly uses the idiomatic
construction so x that y where y is a subordinate
clause that explains or describes x: So debilitating
that it has become. … It clearly refers to
schistosomiasis, which is correctly modi? ed by
the adjective debilitating.
A Correct. In this sentence, the pronoun
reference is clear, and the so x that y
construction is concise.
B ? e noun debilitation creates an awkward,
wordy alternative and a slight change in
meaning; the subordinate clause is not
introduced by that; economical does not have
the same meaning as economic.
C ? e construction so x as to y is not a correct
idiom.
D ? e construction introduced by such is
awkward and wordy; debilitation is also
awkward and slightly di? erent in meaning;
that is omitted; economical does not have the
same meaning as economic.
E ? e noun debilitation creates an awkward,
wordy alternative and a slight change in
meaning; economical does not have the same
meaning as economic.
? e correct answer is A.
接下来请看新prep174的题目：
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
答案选A，此处认为C比A复杂了，我没有异议。但是对于og那题，我选了C，实在不知道为什么错。难道是因为倒装么？但是官方解释里面并没有提到这个问题。斑竹NN们出现一下吧~谢了

happyself

谢谢斑竹，我自己顶一下~~~求解释呀求解释。吼吼

shijiaxin13

应该是so ··· as to中间的so之后只能用adj.或adv.的原形吧，不能是一个句子

happyself

谢谢楼上，我现在明白了。

loverwy

OG C 错的原因是因为 so as to不可以用倒装结构。