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The CDL general knowledge test is required to be taken by all CDL applicants. The District of Columbia CDL test consists of 50 questions. To pass, you must correctly answer at least 40 questions (80%). The general knowledge test covers the contents of the District of Columbia CDL Manual. All CDL applicants (Class A, B and C) must study the following sections: Driving Safely, Transporting Cargo Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Vehicle Inspection Test, Basic Control Skills Test, Road Test. In addition, the Class A CDL test will include questions based on the Combination Vehicles section. Take this CDL practice test now to prepare for the actual DC general knowledge test! To get your CDL, you must pass both the knowledge and skills tests. CDL knowledge tests include: General Knowledge, Passenger Transport, Air Brakes, Combination Vehicles, Hazardous Materials, Tanker Vehicles, Doubles/Triples, School Bus, Firefighter. Depending on what class of license (A, B or C) and endorsements you need, you must take one or more knowledge tests. A special endorsement is also required to drive certain types of vehicles. The following endorsements may be used with a Class A, B or C CDL: HazMat (H), Tank Vehicles (N), Tank Vehicles Transporting Hazardous Materials (X) and Passenger Transport (P). The School Bus endorsement (S) is only available for Class A or B CDL, and the Doubles/Triples endorsement (T) is only available for Class A driver's licenses.
1. To test the parking brake:
check that all shut-off valves are in the open position.
step on and off the brake pedal to reduce air pressure.
gently try to pull forward with the parking brake on.
turn off the engine.
2. When using a fire extinguisher, you should stay:
as far away from the fire as possible.
at least 10 feet away from the fire.
as close to the fire as possible, without getting burnt.
at whatever distance you think is safe.
3. Rust around wheel nuts may mean:
the weather is wet.
the wheels or rims have had welding repairs.
the nuts are loose.
the nuts are too tight.
4. You should check wheel bearing seals for:
broken leaf springs.
illegal stickers.
5. The best way to test the trailer service brakes is to:
put the handbrake on when there are no vehicles around you.
accelerate to the maximum possible speed, then apply the trailer brakes fully.
pull forward quickly, then apply the trailer brakes with your hand control.
None of the above.
6. If the ABS is not working:
you should immediately reduce your speed.
the truck will have no brakes.
the truck will still have normal brakes.
All of the above.
7. Which of the following statements about retarders is NOT correct?
You should turn the retarder off whenever the road is wet, icy, or snow covered.
Retarders help slow a vehicle, reducing the need for using brakes.
Retarders help you avoid skids.
Retarders reduce reduce brake wear.
8. What is a pull up when referring to truck driving?
A driving maneuver used to pull your vehicle over to the side of the road and stop.
Using the speedometer to know when to shift up.
A specific maneuver used to decelerate smoothly in the exit lane.
When a driver stops and pulls forward to get a better position.
9. How far should you scan ahead when driving?
12-15 seconds
One block at lower speeds
A quarter of a mile at highway speeds
All of the above.
10. To prevent drowsiness you should:
drive at night.
eat frequently.
drive with a passenger.
keep the cab warm.
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DC CDL Knowledge Test

Number of questions: 50
Correct answers to pass:40
Passing score:80%
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