请教 大全 sec3 - 23

billion

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

这句话是什么意思?---------怎么也看不明白

另外, 之所以不选A的原因真的只是?----------In A, the logical subject of " to demostrate" probably  is " a canon", while " in demostrating" focus the way in which it is helpful (carefield 版主的解释http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=18782)

还有其他理由吗?

likui

说点background帮助你理解～

就是说呀，飞着的鸟虽然小，但是和飞机撞上了破坏是巨大的～

然后有人就创造条件用大炮制造这种情况～

得出了正如第一句所说的结果～

“据美国空军官员称～”

我就是U.S. Air Force的～嚯嚯～

billion

According to United States Air Force officials, has proved helpful to demonstrate what kind of damage can result when .
Likui版主的解释非常风趣,可我还是不特明白: 关键是看不出"a cannon shooting dead chickens at airplanes "(可不可以理解成用大炮打蚊子---喻大材小用) 这句话和"jets fly into a flock of large birds"到底有什么意思上的联系,

billion

Likui版主的解释非常风趣,可我还是不特明白: 关键是看不出"a cannon shooting dead chickens at airplanes "(可不可以理解成用大炮打蚊子---喻大材小用) 这句话和"jets fly into a flock of large birds"到底有什么意思上的联系

请再解释得详细一些,谢谢!

另外, A 选项为什么错了?

leeon

shooting dead chickens at airplanes has proved helpful to demonstrate

A选项两个错误：helpful in doing/help (to)do；分词做定语和定语从句做定语的区别。

billion

谢谢 Leeon !