Foreign trade, the ____ of goods between nations, takes place for many reasons.

The____of the Itaipu Dam took 30 000 people seven years.

The police say there is a $50,000 _______ for any information that helps them find the killer.

There are usually at least two _____ of looking at every question.

David gave us a vivid            of his trip to Mount Huangshan after his return.