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1.        Unlike a hurricane, which can be observed from within, a tornado is so small that such a study has not been practical.

(A) that such a study has not been practical

(B) that studying it that way has not been impractical

(C) for such studies as this to have been impractical

(D) as to not make such a study practical（A）

(E) as to be impractical of study

what 's difference between A and E???

The inf. has been given before "such, "observed from within".

谢谢jerjer！！

但是我总觉得用such+n.，前面出现过该n.

例：OG181

181. Because of the enormous research and

development expenditures required to survive in the electronics industry, an industry marked by rapid innovation and volatile demand, such firms tend to be very large.

(A)  to survive

(B)  of firms to survive

(C)  for surviving

(D)  for survival

(E)   for firms' survival