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View All PlansDC CDL Combination Vehicles Practice Test 3 2025
A major step toward earning your Class A CDL is passing the Combination Vehicles Knowledge Test. You must have that class of license to legally drive combination vehicles in the District of Columbia. The exam consists of 20 multiple-choice questions, and you must answer at least 16 (80%) correctly to pass. That doesn’t leave much room for error. Not only that, the test covers a wide range of topics, including safe driving, preventing trailer skids and jackknives, air brake systems in combination vehicles, coupling and uncoupling procedures, and inspections. As daunting as that may sound, rest assured, our experts have designed exactly what you need to pass the official knowledge exam on your first attempt.
There are other steps necessary for obtaining your Class A CDL. You must complete all Entry-Level Driver Training (ELDT) through an FMCSA-registered provider before scheduling a CDL skills test, where you must prove your skills behind the wheel of a combination vehicle. Even before that, you will need to obtain your Commercial Learner’s Permit (CLP) and hold it for a minimum of 30 days before scheduling your skills test. Make sure you review the timeline of requirements while studying for the official knowledge exam.
If you fail the Combination Vehicles Knowledge Test, you must wait at least one business day before retaking the exam, and retest fees may apply. One practice test helps to ensure you don’t face second attempts or additional fees. Our Free DC CDL Combination Practice Tests mimic the official exam format and provide real-time feedback, question hints, and detailed explanations to help you master the material as you go, instead of withholding feedback until the end of your session. Furthermore, we offer an entire series of DC-specific practice tests. Once you’ve mastered this one, check out another one here: https://driving-tests.org/district-columbia/dc-cdl-combination-test/.
The majority of combination vehicles use air brakes. You must pass the Air Brakes Knowledge Test and a skills test in a vehicle with air brakes to remove restrictions from your CDL that would bar you from driving air brake–equipped vehicles. Visit our Air Brakes Practice Tests here to fully prepare for that knowledge test: https://driving-tests.org/district-columbia/dc-cdl-air-brake-practice-test/. In addition to the Class A license, you can pursue endorsements to broaden your career opportunities, like the (H) Hazardous Materials endorsement. And yes, we have practice tests for that as well: https://driving-tests.org/district-columbia/dc-cdl-hazmat-practice-test/.
Earning a Class A CDL opens the door to employment in DC’s freight, construction, logistics, and delivery industries. Get started now!

Verified for accuracy: October 2025
Reviewed by Steven Litvintchouk, M.S.
Chief Educational Researcher (ACES member)
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