I live in Indiana and don't know if the tests are the same elsewhere, but here General Knowledge is 50 questions and I think your allowed to miss 10, Air Brakes 25 questions not sure on the amount allowed to miss, and if she wants Haz-Mat I think it is around 20-25 questions and your allowed to miss up to 7.
Here's a link with [link:www.4dmv.com/commercial_drivers_license.htm|CDL Info].