This afternoon Mr Smith will give us a report on nuclear energy , which is well worth _____.

The bridge is so important to the people here that once ________ it must be carried out without delay.

Aluminum isn’t found free in nature, owing to its always ____ with other elements, most commonly with oxygen. 

He ran as fast as he could _____ to catch the early bus.

The project ______ by the end of 2007, will expand the city’s telephone network to cover 2,000,000 users.