When the soldiers marched into the valley,they suddenly found themselves()by enemy forces.

问题描述:

When the soldiers marched into the valley,they suddenly found themselves()by enemy forces.
答案:A、surroundingB、surroundedC、be surroundedD、having surrounded
请问正确答案是哪个?并加以解释,谢谢!
请问xszsn为什么答案C不对呢?

find oneself doing/done 由于是被动因此用B项