GMATGuruNY wrote:

mundasingh123 wrote: The construction helpful in + gerund is appropriate when the action of the gerund is the area in which help is wanted. In the SC above, demonstrating what kind of damage is the area in which the cannon can prove helpful.
The construction helpful + infinitive is appropriate when the action of the infinitive is helpful in performing another action or achieving another goal:
When raising children, it can be helpful to demonstrate good manners.
In the sentence above, the action to demonstrate good manners is helpful in performing another action (raising children).

Hi Guru,
Then E ( helpful + gerund) changes the meaning of the original sentence which has the infinitive conveying that a goal is being achieved.
So do we reject option A because of the progressive tense "shooting"

mundasingh123 wrote:

GMATGuruNY wrote:

mundasingh123 wrote: The construction helpful in + gerund is appropriate when the action of the gerund is the area in which help is wanted. In the SC above, demonstrating what kind of damage is the area in which the cannon can prove helpful.
The construction helpful + infinitive is appropriate when the action of the infinitive is helpful in performing another action or achieving another goal:
When raising children, it can be helpful to demonstrate good manners.
In the sentence above, the action to demonstrate good manners is helpful in performing another action (raising children).

Hi Guru,
Then E ( helpful + gerund) changes the meaning of the original sentence which has the infinitive conveying that a goal is being achieved.
So do we reject option A because of the progressive tense "shooting"

Answer choice A can be eliminated because the idiom helpful to demonstrate is being used incorrectly and does not convey the intended meaning of the sentence.

As noted above, helpful + infinitive is appropriate when the action of the infinitive is helping to perform another action. In A, helpful to demonstrate would be appropriate only if the officials were demonstrating in order to help shoot the cannon. For A to be correct, the verbs would have to swap positions:

When demonstrating the kind of damage that can result when a jet flies into a flock of large birds, United States Air Force officials find it helpful to shoot a cannon at dead chickens.

Regarding the use of the progressive in A: the construction a cannon shooting is not grammatically incorrect, but since the cannon isn't constantly shooting, a cannon that shoots is better.

GMATGuruNY wrote:

mundasingh123 wrote: Answer choice A can be eliminated because the idiom helpful to demonstrate is being used incorrectly and does not convey the intended meaning of the sentence.

As noted above, helpful + infinitive is appropriate when the action of the infinitive is helping to perform another action. In A, helpful to demonstrate would be appropriate only if the officials were demonstrating in order to help shoot the cannon. For A to be correct, the verbs would have to swap positions:

When demonstrating the kind of damage that can result when a jet flies into a flock of large birds, United States Air Force officials find it helpful to shoot a cannon at dead chickens.

Regarding the use of the progressive in A: the construction a cannon shooting is not grammatically incorrect, but since the cannon isn't constantly shooting, a cannon that shoots is better.

Sir,this is a nugget of extremely valuable knowledge that i have gained today.
Thanking you for being here

mundasingh123 wrote: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
The OA is E

I chose A.
Helpful to + verb is also correct.
What is the difference between A and E?