1. What has your instructor told you to do in the circuit?
2. What licences/permits/certificates you need to do to be able to fly legally?
3. What do you need to do around an aeroplane before you fly it?
4. What must you do to avoid colliding with other aeroplanes in the circuit?
If you can explain these things then you have a sufficient grasp of air law to pass the exam. Knowledge of some obscure things will get you extra points to give you bragging rights about how you aced the exam.