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. This questions appears in the following tests: Alaska Air Brakes Arizona Air Brakes Connecticut Air Brakes Hawaii Air Brakes Iowa Class B Knowledge Test Louisiana Air Brakes Michigan Class A Knowledge Test New Mexico Class B Knowledge Test New Mexico Air Brakes North Carolina Air Brakes Ohio Air Brakes Rhode Island Class B Knowledge Test Rhode Island Double South Carolina Class B Knowledge Test South Dakota Air Brakes Tennessee Air Brakes Vermont Class B Knowledge Test Washington Class B Knowledge Test Wyoming Air Brakes