for; for the purpose of; in order to

And I know you didn't do this just to win an election. And I know you didn't do it for me. You did it because you understand the enormity of the task that lies ahead. For even as we celebrate tonight, we know the challenges that tomorrow will bring are the greatest of our lifetime: two wars, a planet in peril, the worst financial crisis in a century.

English has become an international language.

The rescue worker searched the area, looking for the child.

We eat so we can live.

What has become of her son?