A．They use a map and the memory of location.
B．They use the sun and the stars.
C．They use a map and the earth’s magnetic field.
D．They have precise sense of time or may use the earth’s magnetic field.

A．To lock up their garages at night.
B．To leave their cars in the garages unlocked.
C．To lock up their cars even when they are kept in locked garage.
D．To park their cars on the roadside instead of in the garage.