When________(face)with a strong enemy,they had always retreated.我认为答案是facing 但是不是啊

问题描述:

When________(face)with a strong enemy,they had always retreated.我认为答案是facing 但是不是啊
请指教

be faced with
这可以记下来当固定短语的从非谓语动词的角度 该怎么理解呢非谓语啊,我认为这个意思有点绕,就是they是被a strong enemy face的,反过来说也就是they是被动,a strong enemy才是主动。