The green belt = an area of land with fields or parks around a town or city, where people are not allowed to build houses or factories by law.

• The green belt has a valuable role in stopping urban sprawl and providing a green lung around towns and cities.
• The green belt and open spaces in our urban and suburban areas must be preserved at all cost for reasons too many to list.

White collar worker = a person who performs professional, managerial or administrative work.

• White collar workers at Mirage car factory have gone on strike over pay and other working conditions.
• White collar workers now work longer hours.

Grey area = something that is a problem, and is not very clear because there are no rules.

• The difference between gross negligence and recklessness is legal grey area.
• There are many grey areas in the law affecting stolen animals.
• There’s a large grey area regarding whether the use of the new surveillance technology is lawful.