The security chief was supposed to prevent dangerous aliens from attacking the ship's crew.

Any time you're out to prevent a team from attacking you in a certain way, that's smart.

You may also take medicine to help prevent the donor cells from attacking your body.

When another woman attempted to prevent the soldiers from attacking her two daughters, she was beaten.

"But what will prevent them from attacking even if they do?"

"What is to prevent them from attacking your ship the moment we are detected on their sensors?"

"I'm not really bad, you know; but we have to pretend to be terrible in order to prevent others from attacking us."

"How many times have you prevented a terrorist from attacking us?"

This prevents the immune system from accidentally attacking the body.

Her mother said she prevented settlers from attacking Palestinian houses.