No car has passed

Jack: Mummy, can I go and play at my friend's house?
Mummy: Of course, but don't cross the road until a car goes by, then you cross.
So Jack went out of the house. After a few hours, Mummy waited anxiously for Jack to come home . Then she found
Jack outside their house.

Mummy: Why are you still here?
Jack: No car has passed by yet, so I haven't crossed the road.