她偷偷地看了他的手机。
tā tōutōudì kànle tāde shǒujī 。
She secretly looked at his phone.
他偷偷地溜进了房间。
tā tōutōudì liūjìn le fángjiān 。
He stealthily sneaked into the room.
他们在偷偷计划一个惊喜派对。
tāmen zài tōutōu jìhuá yígè jīngxǐ pàiduì 。
They are covertly planning a surprise party.