| 求助og39题，以前没有讨论过的！谢谢大家了！
39. For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military equipment, a method to protect warriors against enemy arrows and spears.
(A) a method to protect
(B) as a method protecting
(C) protecting
(D) as a protection of
(E) to protect
Choice C is best because the participle protecting begins a phrase that explains what the shields did. Choices A and B awkwardly use the singular word method to refer to items of military equipment rather than to the use of such items. Also, a method of protecting would be more idiomatic than a method to protect in A or a method protecting in B. In B and D, as is incorrect; also, a protection in D has no noun for which it can logically substitute. Choice E is incomplete; used to protect would have been acceptable.
首先， a protection in D has no noun for which it can logically substitute. 不是很能理解？
另外，对于as，刚才查了“英语语法大全”，没有发现d中的as使用有什么不对，请教大家！
最后， a method of protecting would be more idiomatic than a method to protect in A or a method protecting in B. 为什么用动名词会好些，请教！
谢谢！ | 
