敲 + (了敲) + Object
敲 (qiāo) means "to knock" or "to tap" and describes the action of striking a surface, typically a door, with one's hand or knuckles. It is often reduplicated as 敲了敲 to indicate a brief, casual knocking action. For example, 敲了敲门 means "knocked on the door."
他走到门前,轻轻敲了敲门。
Tā zǒu dào mén qián, qīngqīng qiāo le qiāo mén.
He walked to the door and knocked gently.
有人在敲窗户,你去看看是谁。
Yǒu rén zài qiāo chuānghù, nǐ qù kànkan shì shéi.
Someone is knocking on the window; go see who it is.
她敲了半天门,里面都没人应。
Tā qiāo le bàntiān mén, lǐmiàn dōu méi rén yìng.
She knocked on the door for a long time, but no one answered inside.