surreptitious

她偷偷拍下了会议的照片，没有人注意到。

She took ___surreptitious photos of the meeting without anyone noticing.

她偷偷摸摸地看了眼手机，确保没人注意到。

She took a ___surreptitious glance at her phone, making sure no one noticed.

他偷偷摸摸地从后门溜进了房间。

He made a ___surreptitious entry into the room through the back door.