Based on 2025 DC commercial driver's license manual
Free District of Columbia CDL Combination Practice Test 2025
This CDL practice test is a great place to start if you’re after the DC Combination Vehicles endorsement. Each of the 25 questions is based on the official 2025 CDL manual. The test is designed to prepare you for the Combination Vehicles portion of your 2025 Commercial Driver’s License exam. There are several answer options, but only one of them is correct. Every time you answer a question, you’ll get immediate feedback with a detailed explanation, so you won’t need to wait until the end of the test to know the correct answers.
Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
Triple-checked for accuracy
What you need to know
9 min to complete
Available in EN and ES
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After you lock the kingpin into the fifth wheel, how should you check the connection?
After you connect the air lines but before you back under the trailer, you should
Which statement best illustrates the "crack-the-whip" effect?
When you inspect the landing gear after uncoupling the trailer, where should the tractor be?
What is the safest way to turn right from a two-way road?
To drive a triple combination vehicle, you must have
To prevent a rollover, cargo should be
Combination vehicles take longer to stop when they are empty than when they are fully loaded, because
If your vehicle gets stuck on a railroad track, you should
Low-slung vehicles can be risky at railroad crossings because
On a double or triple vehicle, which wheels offtrack the most?
When you're pulling doubles or triples, the shut-off valves should always be
On a trailer, where is the yellow antilock brake (ABS) malfunction lamp located?
Even before antilock braking systems (ABS) were required, some vehicles already had them. How can you check if your vehicle has ABS?
An antilock braking system (ABS) is useful
After coupling, make sure that the air lines are not crossed. How should you do this?
During uncoupling, you should disconnect the electrical cable and
Before you start to uncouple, you must
You can confirm that air is going to all brakes in your trailers by
To uncouple a loaded trailer, after the landing gear has made firm contact with the ground, you should
If the trailer has antilock brakes (ABS) but the tractor doesn't,
To test the tractor protection valve, charge the trailer air brake system, turn off the engine, and
If your test of the tractor protection valve is successful,
The tractor protection valve is designed to close automatically if the air pressure falls into the pressure range specified by the manufacturer, typically
As part of your vehicle inspection test, if your vehicle is equipped with air brakes and has a trailer, you will inspect the air connections between the truck or tractor and the trailer. Make sure that the ________ are locked in place and free of damage or air leaks.
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Our commitment to accuracy and quality in our practice tests
Explore our rigorous, multi-tiered verification process that ensures each question mirrors the official manual for unparalleled accuracy.
Written by Andrei ZakhareuskiUpdated over a week ago
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