请教问题2道

In the most common procedure for harvesting forage crops such as alfalfa, as much as 20 percent of the leaf and small-stem material, which is the most nutritious of all the parts of the plant, shattered and fell to the ground.

(A) which is the most nutritious of all the parts of the plant, shattered and fell

(B) the most nutritious of all parts of the plant, shatter and fall

(C) the parts of the plant which were most nutritious, will shatter and fall

(D) the most nutritious parts of the plant, shatters and falls.

(E) parts of the plant which are the most nutritious, have shattered and fallen

这里的主语应该是20%呢还是leaf和 small-stem material 呢?

(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 helpfull 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

整句话什么意思呢? 为什么大炮和撞机有关呢

万分感谢

用大炮把死鸡射向飞机的办法来了解喷气式飞机在飞入鸟群时可能造成的损伤。