Final answer:
The main forms of terrorist attacks on airports include bombings, hijackings, and armed assaults.
Step-by-step explanation:
The main forms of terrorist attacks on airports include bombings, hijackings, and armed assaults. In some cases, terrorists have used commercial airliners as weapons by hijacking them and crashing them into targets, as seen in the 9/11 attacks. Other forms of attacks on airports may include the use of weapons, such as firearms and explosives, targeting passengers, airport employees, or infrastructure.