关于keep from 用法的 一道题！！

陈星澍

OG-10 183. Archaeologists in Ireland believe that a recently discovered chalice, which dates from the eighth century, was probably buried to keep from being stolen by invaders.

(A) to keep from

(B)to keep it from

(C) to avoid

(D) in order that it would avoid

(E) in order to keep from

我的疑问在于 答案中为什么 要有it ？ 如果要是用 avoid 的话 又如何 修改C选项呢？？
请高手指点！！！ Gracias

jaze

句子的主要意思是 一个杯子埋着是为了防止其被偷走
如果 用to keep from的话，那keep的主语就是 杯子了，显然不和逻辑啊
avoid同样道理
但是如果是keep  it from就不一样了，it是主语  chalice，这就说明是埋了它是为了防止它被偷走