1. There has been much posted on here about modal verbs. I am sure you will be able to find a post or posts that will answer any questions you might have.
2. Say:
take a qualification exam
graduate
Those teachers get paid by the hour.
government school
I passed the exam. (You don't need to say you passed it successfully.)
2. Say:
take a qualification exam
graduate
Those teachers get paid by the hour.
government school
I passed the exam. (You don't need to say you passed it successfully.)