다고요

Polite 'you're saying that...?'

Echoes back a statement politely, usually to check it or to register surprise: you also worked as a police officer?, a lot of people got freesia?, who did you hear it from?, but you said rain got inside? It is the standard interview move for picking up what the other person just said and turning it into the next question. Without the question mark it insists on your own words, as in the line saying they couldn't even imagine it.

Register: polite