Alexander decided to prevent them from joining their forces.

"Prevention at an early age gives kids an opportunity they need to prevent them from joining the gang," he said.

Before we panic, let's prevent kids from joining gangs in the first place.

The administration is determined to prevent Iraq from joining the nuclear club.

There was nothing in the law that would prevent the employees from joining any other collective bargaining group.

And nobody prevented me from joining in the fun.

How can we prevent the soldiers from joining the war lords once they have been trained?

It should not prevent anyone from joining the European Union.

They are effectively preventing, or at least discouraging, others from joining in.

However, his family prevented him from joining the army.