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Drivers who want to drive combination vehicles must pass the combination vehicles test. The District of Columbia CDL combination test consists of 20 questions, and you'll need at least 16 correct answers to pass (80%). The test covers the combination vehicles section of the District of Columbia CDL Manual. Take this practice test now to prepare for the actual DC CDL combination test!
1. When driving in very hot weather, the heat will increase the chances of:
loss of hydraulic pressure.
suspension system defects.
tire failure.
ABS malfunction.
2. Before starting down a hill, you should:
apply the brakes hard.
look for an escape route.
release the accelerator and shift to Neutral at the same time.
slow down and shift to a lower gear.
3. Which of the following is NOT part of the procedure to raise the landing gear?
Raising the landing gear all the way up
Using the high range gear, if equipped, to begin raising the landing gear
Safely securing the crank handle, after raising the landing gear
Using the low range gear, if equipped, to begin raising the landing gear
4. Combination vehicles _________ than single CMVs.
require more driving skill
are much easier to drive
are safer in bad weather
All of the above.
5. What is the minimum tread depth for tires other than front tires?
4/16 inch
2/32 inch
4/32 inch
8/32 inch
6. When the ______ closes, it stops any air from going out of the tractor.
height control valve
hand valve
tractor protection valve
alcohol evaporator
7. If are being followed closely, you should:
flash your brake lights.
decrease your following distance.
change lanes quickly.
increase your following distance.
8. You should use chocks when parking a trailer without spring brakes because:
it helpsĀ prevent skids.
it is required by law.
the brakes will hold only as long as there is air pressure in the trailer air tank.
it helpsĀ prevent brake failure.
9. With brake drums, if brakes become too hot:
the brakes will supply too much power to the drive wheels.
your ABS will malfunction.
the brakes may stop working.
the air compressor will kick on to cool the brakes.
10. What is the proper following distance for a 50 foot truck traveling at 50 mph?
6 seconds
5 seconds
10 seconds
25 seconds
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CDL Combination Test (DC)

Number of questions: 20
Correct answers to pass:16
Passing score:80%
Number of questions: 20
Correct answers to pass:16
Passing score:80%
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