hardest part for me when i got my class A CDL was like the other person said, the pre/post trip inspection both inside and out, reason being is that for an 18 wheeler its about 180 parts you have to touch and say the actual name, and you do have to actually touch the parts not just point to it and you have to say the actual part name, not say "you check that and then that" and you also have to clarify what your checking for, as in being loose, leaking or like the steering shaft doesn't rotate more than 2 inches, of course some are the same parts so its not 180 seperate parts, just 180 parts all around the truck, and usually DMVs are strict on the inspection test because its a safety thing