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 这道题我选的E,答案是A,为何A比E好,求助!