Accounting Information Systems and a horrible professor

I'm going back to school for a certificate, and I need to pass this class with a C to move on. The problem is that the professor is ridiculously hard. Not just a tough grader, he's not even fair with his tests. He does easy examples, and when we ask for something harder, he says not to worry about it, that we won't need it for the test. He then gives us tests that grill us worse than anything the book has. How can you even prepare for something like that?