Practice question

Poisonous fumes can enter a truck's cab due to:

  1. A defective exhaust system.
  2. The wrong type of fuel being used.
  3. A lack of oil in the engine.
  4. Under-inflated tires.

Answer: A — A defective exhaust system.

The correct answer is shown above. Try the full quiz for additional practice.

Practice more: Illinois CDL Class B Knowledge Test 1 →