The purification of this lake is left to the power of nature.

We need a device to purify this water.

This water is purified through a special filtration system.

This water passes through a special device to filter out bacteria.

This system is very efficient.

This is a human with a special ability.

His artwork has a special charm.

On cold days, cold water is especially delicious.

My brother works as a systems analyst.

My computer needs a new operating system.