Here is a situation:
(Jack and Dorothy are in the car)
Silence. They pass Blumergton. Dorothy looks out of the window, her face is obviously surprised.
Silence again. They pass Himilgreens.
Jack: "I must tell you something"
Dorothy: "What is it?"
Jack: "We are not going to Darwinhill"
Dorothy: "I know that"
Jack: "How come you know that?"
Dorothy: "Otherwise we would've not passed Blumergton"
or should it be "Otherwise we would not pass Blumergton" or should it be some other way?