885 S3-10,23

xu1jf

10. For many people, household labor remains demanding even if able to afford household appliances their grandparents would find a miracle.
(A) even if able to afford household appliances their grandparents would find a miracle
(B) despite being able to afford household appliances their grandparents would find a miracle
(C) even if they can afford household appliances their grandparents would have found miraculous
(D) although they could afford household appliances their grandparents would find miraculous
(E) even if they are able to afford household appliances which would have been a miracle to their grandparents
C答案中,如何能感觉出它的完成时态来?

23. 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. A为何不对?现在分词与定语从句通常有何不同?再一个,句子中如何感觉出有完成式的意思来? Prove in doing 是固定用法吗?

lshine

第一个不是完成时，是虚拟语气。

第二个中的固定搭配是helpful in doing