一道OG的题目

thumbbunny

OG12中语法第30题。
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

为啥不选A

CrackingGMAC

同位语要求要对等。a method 不可能是 equipment，一个是做事方法，一个是物。
其实OG解释得相当清楚了。