US forces were then called in to help clear out the street.

If he called on us to help him in his work, we were to do so.

Until called upon to help, he was not required to do so.

And along with many other nations, we've been called upon to help.

The army was then called in to help the police.

That's why I felt called upon to help a friend once.

This is why you two have been called in to help us.

It would be best to leave, to call others to help.

More than 1,000 soldiers were called to help the population.

Finally he called in an assistant to help him think.