Practice question

Why should the trailer hand valve not be used to straighten a jackknifing trailer?

  1. It can lock trailer wheels and make the skid worse
  2. It always activates ABS on all axles
  3. It is designed for parking only and cannot apply brakes
  4. It raises engine RPM

Answer: A — It can lock trailer wheels and make the skid worse

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Practice more: DC CDL General Knowledge Practice Questions - District of Columbia Commercial Driver License General Knowledge Test Exam →