Who's, mine? Don't worry about it.
The tanks in the practice missions are scary accurate. Not realistic when you look at the multiplayer game. You have to keep moving, or else they'll lock onto you. Fire a few bullets at them, swerve wildly, and attack again from a different angle. Don't try to bomb them.
In all honesty, the practice missions aren't any fun. Play multiplayer, you'll learn much faster.