Question When leaving your vehicle unattended: Answers The parking brake must be always be used. The parking brake should never be used. Windows in the cab should be lowered. Explanation Always apply the parking brake when leaving your vehicle unattended. Take a FREE Practice Test Now This questions appears in the following tests: Kentucky Knowledge Test Class A , Wyoming Knowledge Test Class A , Maine Knowledge Test Class B , Rhode Island Knowledge Test Class B , Hawaii Air Brakes , Idaho Air Brakes , Louisiana Air Brakes , Michigan Air Brakes , New Hampshire Air Brakes ,