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(A)
E.gradual enough so that one cannot distinguish them
08prep上说so as to 是可以使用的,但是我在OG 上看到两次“The construction so x as to y is not a correct idiom” "So as to marry is not idomatically correct"这个到底要怎么判断呢?纠结ing~~~~