请教道pp174~

misssaint

Often major economic shifts are so gradual as to be indistinguishable at first from ordinary fluctuations in the financial markets.    c

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

为什么c不可以呢

AlienX

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