4 sentences

1. 他坐在窗边发呆。

   tā zuò zài chuāng bian fā​dāi.

   He sat by the window, staring blankly.

   Source: Dong Chinese Dictionary

2. 他总是一个人坐在窗边发呆。

   tā zǒng shì yī gè rén zuò zài chuāng biān fā​dāi.

   He is always sitting by the window in a daze.

   Source: Dong Chinese Dictionary

3. 他坐在窗边发呆，不知道在想些什么。

   tā zuò zài chuāng biān fā​dāi, bù zhī​dào zài xiǎng xiē shén​me.

   He sat by the window staring blankly, lost in thought.

   Source: Dong Chinese Dictionary

4. 听到好友出事的消息，他吓得整个人都发呆了。

   tīng​dào hǎo​yǒu chū​shì de xiāo​xi, tā xià de zhěng​gè rén dōu fā​dāi le.

   Hearing the news about his friend's accident, he was stunned into a daze.

   Source: Dong Chinese Dictionary