有人潜伏在树后，偷偷观察着我们的营地。

Someone ___lurked behind the trees, secretly watching our campsite.

黑暗的森林中总是潜伏着未知的危险。

Unknown dangers always ___lurk in the dark forest.

他在论坛里潜水了几个月才发表第一条评论。

He ___lurked on the forum for months before posting his first comment.