OG12 SC30

pattytraine

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

问题：我知道答案选C 也明白原因

但是E选项 因为不定式to do前一般没有句号 所以这个错了而且明显没有C解释好
但是OG的解释“Although the infi nitive to protect would work
if it were not preceded by a comma, it
cannot act as a nonrestrictive adjectival
phrase modifying items.”

如果删掉逗号也不对的原因是什么？有哪位可以解释的更详细一些吗？谢谢！

pattytraine

∵如果没有逗号的话，则为“……essential items of military equipment to protect warriors……”
形容的可以是essential items 或者是 military equipment 会产生歧义

这种理解对吗？希望有人可以指教