Remember your macros. MAC32 DVIR stuff about brakes, and a sample load so that you can trip plan. If you don't pass, it's no big deal. It has no bearing on how well you can operate a CMV.
I might be a little late to this party, but if you've got a chance, why not sit in a Denny's when the truck isn't moving and read over the Driver's Handbook? There are lots of things in there your mentor (or maybe just the one I had) won't tell you.
