HSK 7–9 grammar · pattern
不知X的
不知⋯⋯的（还以为⋯⋯）— anyone who didn't know would think
Pattern
+ + +
( ) can be left out · other words may come before, between and after
How it works
不知…的 turns "those who don't know" into a noun phrase, and the 还以为 clause reports the wrong conclusion they would draw. The speaker uses it to point out how misleading a scene looks.
Examples
不知道的还以为你们是兄弟呢。
Bù zhīdào de hái yǐwéi nǐmen shì xiōngdì ne.
Anyone who didn't know would think you two were brothers.
不知情的还以为他生气了。
Bù zhīqíng de hái yǐwéi tā shēngqì le.
Someone not in the know would think he was angry.
Related
See it in a story
In the app, 不知X的 is underlined wherever it appears in the stories you read, and practised with sentences from them. Free.