Hi there, I am really struggeling with my SC portion. I am specially afraid of the -ing form where ever it appears...can someone suggest where can I find resources to get a better grip on the "-ing" thing.


Here is an example:


According to the 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 flok 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 chicken at airplanes has proved helpful in demonstrating

I can easily zero down onto (a) and (e). But then why is (e) the correct answer (which it is) and not (a).
Is shooting here a partciple? If not what is it?...please help !