n.窥视孔
The guards checked at the peephole before entering.
卫兵进入前透过门镜检查了一下。
A one - way peephole in a door.
窥视孔门上 单向 的窥视孔.
Through the peephole I said to him: " My key off in the lock. "
对着门上的窥孔,我对他说: “ 我的钥匙断在锁里了. ”