Tennessee CDL — General Knowledge practice
Tennessee CDL — General Knowledge: Alcohol & Drugs practice test
Blood alcohol limits, zero-tolerance and implied-consent laws, and how alcohol and drugs — legal or not — affect your driving.
Content reviewed against official driver handbooks · August 12, 2026
14 questions · pass with 11 correct. You get instant feedback and an explanation after every answer.
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12 sample Alcohol & Drugs questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. What is the only thing that will actually sober up a person who has been drinking?
Correct answer: Time
Only the passage of time sobers you up; black coffee, a cold shower, or fresh air will not.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
2. At what blood alcohol concentration is it illegal to operate a commercial motor vehicle?
Correct answer: .04 percent or higher
It is illegal to operate a CMV with a blood alcohol concentration of .04 percent or higher.
Source: Tennessee CDL Manual — Section 1: Introduction (Alcohol and Disqualifications)
3. What is the penalty for a second major alcohol or drug offense in a CMV?
Correct answer: Loss of the CDL for life
A second offense results in loss of the CDL for life.
Source: Tennessee CDL Manual — Section 1: Introduction (Alcohol and Disqualifications)
4. How long will a driver lose the CDL if the alcohol offense occurs while hauling placarded hazardous materials?
Correct answer: At least three years
If the offense happens while the vehicle is placarded for hazardous materials, you lose the CDL for at least three years.
Source: Tennessee CDL Manual — Section 1: Introduction (Alcohol and Disqualifications)
5. Which part of the brain does alcohol affect first as the BAC rises?
Correct answer: The part controlling judgment and self-control
Alcohol first affects the part of the brain that controls judgment and self-control, which are essential for safe driving.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
6. A prescription drug given by a doctor may be used while driving only if what is true?
Correct answer: The doctor says it will not affect safe driving ability
You may use a doctor-prescribed drug on duty only if the doctor tells you it will not affect your safe driving ability.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
7. What happens to a driver found with a detectable amount of alcohol below .04 percent while operating a CMV?
Correct answer: Placed out of service for 24 hours
A driver with any detectable alcohol under .04 percent is placed out of service for 24 hours.
Source: Tennessee CDL Manual — Section 1: Introduction (Alcohol and Disqualifications)
8. By operating a CMV, what have you agreed to regarding alcohol testing?
Correct answer: Consent to alcohol testing
By operating a CMV you are deemed to have given consent to alcohol testing.
Source: Tennessee CDL Manual — Section 1: Introduction (Alcohol and Disqualifications)
9. How can common over-the-counter cold medicines affect a driver?
Correct answer: They can make the driver drowsy and unsafe
Cold medicines and other legal drugs can make a driver drowsy or otherwise impair safe driving ability.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
10. Which driving abilities does alcohol impair?
Correct answer: Reaction time, depth perception, night vision, and muscle control
Alcohol dulls your reaction time, depth perception, night vision, and muscle coordination while also clouding judgment.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
11. Which of these servings contains about the same amount of alcohol?
Correct answer: A 12-ounce beer, a 5-ounce glass of wine, and a 1.5-ounce shot of liquor are about equal
A 12-ounce beer, a 5-ounce glass of table wine, and a 1.5-ounce shot of 80-proof liquor all contain about the same amount of alcohol.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
12. About how much alcohol can the liver process in an hour?
Correct answer: About one-third of an ounce per hour
The liver removes only about one-third of an ounce of alcohol per hour, and this rate is fixed.
Source: Tennessee CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
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