The performance system was also used to replace specialized workers.

It can be used to replace certain kinds of sugar.

Troops have been used more than 30 times since the second world war to replace striking workers.

The car used to replace walking for the 'beat' police officer.

They are also used to replace offerings in kind, like animals or food.

They are used to replace energy before, during and after vigorous exercise.

It used them to replace older models when they wore out.

The organs can then be used to replace those of the sick person.

It can be built into a new building or used to replace an existing roof.

Artificial systems can be used to replace the original ones when, eventually, they do wear out.