2024 MD CDL Practice Test: Class A - Test Based on 2024 MD CDL Handbook 12. What color is the trailer air supply knob? A Black. B Yellow. C Green. D Red. Next More 12/30 Progress 0 Errors Restart Next Next Class A - Test 1 Back to Test List Bus - Test 3 Class A - Test 2 Challenge Library 12 More MD CDL Practice Tests 2 Class A - Test 2 3 Class A - Test 3 4 Class A - Test 4 5 Class A - Test 5 6 Class A - Test 6 7 Class A - Test 7 8 Class A - Test 8 9 Class B - Test 10 Class B - Test 2 11 Class B - Test 3
