Final answer:
When a car with anti-lock brakes makes an emergency stop suddenly, firm pressure should be applied to the brake pedal until the car comes to a stop. This enables the anti-lock brake system to effectively control the braking force and prevent the wheels from locking up and skidding.
Step-by-step explanation:
When a car with anti-lock brakes makes an emergency stop suddenly, it is important to apply firm pressure to the brake pedal until the car comes to a stop. This is because anti-lock brakes rely on a system that modulates the pressure on the brakes to prevent the wheels from locking up and skidding. By maintaining firm pressure on the brakes, the anti-lock brake system can effectively control the braking force and allow the car to stop safely without losing control.