When people say “they're engaged,” the phrase “to be married” 'is understood'. [=“they're engaged” is understood to mean “they're engaged to be married”]
We still don't fully 'understand' the causes of the disease. = The causes of the disease are still not fully 'understood'.
He believed it 'was understood' [=believed that everyone had agreed] that he would be paid for the work.
(..) (officer shouting excitedly) Hey, I want it... I want it on the record. Frank Abagnale surrendered of his own accord. Understood? Understood? Where are you taking him? (speaking in French) I'm... I'm supposed to go. (..)2002 Catch Me If You Can
(..) When I get inside, you go back to the front seat and wait. Even if a cop comes and writes you a ticket you don't move the car, understood? Dad, wha-what's all this for? You know why the Yankees always win, Frank? 'Cause they have (..)2002 Catch Me If You Can