请教OG11黄皮 24题

题目：

For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military eauipment, a method to protect warriors against enemy arrows and spears.

(A) a method to protech

(B) as a metod protecting

(C) protecting

(D) as a protection of

(E) to protect

答案选C，可以理解。但是我不理解为什么B和D中的as用得不对呢？特别是D选项解释,beginning the phrase with as is incorrect。哪位大侠指导一下为什么是不正确的呢？另外，后面这部分，有没有可能用as来引导？还需要做哪些改动呢？

protecting....  是前述句的伴随状语，也就是 前述句一系列动作的伴随

由此，一系列动作 不可以 as a metod 或as a protection 。动词与动词对应，名词与名词对应。

不知理解的对不对？

老大，前面哪有一系列的动作呀？明明动词就只有一个？？？