Q
21. You are coupling a tractor to a semi trailer and have backed up but are not under it. What should you hook up before backing under the semitrailer?
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AThe emergency and service air lines.
BThe electrical service cable.
CNothing, back up and lock the fifth wheel.
Detailed Explanation
The correct answer is "The emergency and service air lines.". This is based on federal CDL regulations and safety standards.
Correct Answer: The emergency and service air lines.
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A shut-off valve:
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Air pressure in the ____ air line is controlled by either the foot brake or trailer hand brake.
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If a trailer begins to skid, the driver should:
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