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General Knowledge
Air Brakes
Combination Vehicles
Doubles and Triples
Tanker Vehicles
Hazardous Materials
Transporting Passengers
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CDL Practice Test
General Knowledge
Air Brakes
Combination Vehicles
Doubles and Triples
Tanker Vehicles
Hazardous Materials
Transporting Passengers
CDL Combination Vehicles Practice Test
Question 1 of 3
What's the purpose of the trailer air supply control?
A
Supplies air to the trailer
B
Engages the trailer air brakes
C
Prevents trailers from becoming decoupled
D
Supplies air to the cab
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