When dealing with something like an exit exam for high school,
anything is fair game.
In fact, here in California schools even set up classes specifically
to help pass the exit exam.
The classes should be almost to the letter as to how the exam will
look, complete with sample questions.
The best way to practice for multiple choice standardized tests,
is to practice doing standardized tests.
As far as content goes, you need to teach what it on the test in a way
that allows students to learn, as well as just do well on the test.
Even though it has a negative connotation, teaching the test is exactly
what you should be doing in this case.
Having said that, there is no reason why you can't teach to the test and
toss other stuff in at the same time.
Stephen C
http://teachersindex.com