你不是去了北面吗
“Weren't you up north?”
THE DIALOGUE REEL
我去了上海
“I went to Shanghai.”
你不是去了北面吗
“Weren't you up north?”
怎么跑去上海了
“How did you end up in Shanghai?”
“Wait, you were supposed to head north, so what on earth were you doing in Shanghai?”
Using '你不是...吗' softens an interrogation while still demanding a logical explanation for an unexpected discrepancy.
LEARNING CHUNKS & PARTICLES
didn't you go to...
A rhetorical question pattern used to express surprise when reality contradicts a previously held assumption.
Turns the negative statement into a rhetorical question seeking confirmation and showing mild astonishment.