求助一道SC

knight

According to United States Air Force official, 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.

b、shooting dead chickens at airplanes has proved itself helpful as 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

请分析此题解题思路和告知prove 用法。谢了先。

请讲一下A、E的区别。晕啊！

knight

多谢两位老大。
另傻傻地问：这里A的分词是表示一直在进行的动作还是经常性动作？偶记得分词和从句的区别是分词表示经常性动作，而从句表示具体情况。对吗？