—Jack can’t concentrate on his lessons recently. —Yes, that might______his low score in the last test.

The best method to _____ the goal of helping the patients with AIDS is to unite as many sympathetic people as possible.

Some time after the rockets and the space shuttle are _____, the rocket will _____ the space shuttle and ____ the sea.

Hardly could he ________ this amount of work in such a short time.

In a way, Pompeii is like a time capsule ____ a frozen moment in history.