大全55

       According to United States Air Force officials, a cannon shooting dead chickens at airplanes has proved helpful to demonstrate what kind of damage can result when jets fly into a flock of large birds.

(A) shooting dead chickens at airplanes has proved helpful to demonstrate

(B) shooting dead chickens at airplanes has proved itself helpful as a demonstration of

(C) shooting dead chickens at airplanes proves itself helpful as demonstrating

(D) that shoots dead chickens at airplanes proves itself helpful to demonstrate

(E) that shoots dead chickens at airplanes has proved helpful in demonstrating

答案是E， 是否没prove itself adj. to这种结构？

有这种结构的

，错的原因是烦琐

从语法角度，我也觉得A指代的可以是句子，也可能是malaria，可是其他的都明确不对，只能选A了.