The air-duct in the building needs to be cleaned regularly.

The air-ducts in the building need to be cleaned regularly.

The construction workers used air hammers to break up the concrete.

The air line in the factory burst, causing a temporary shutdown.

I booked my tickets with two different air lines.

I used an air hammer to break up the concrete.

The supplies were air-dropped to the remote village.

The military is air-dropping supplies to the remote village.

Air transport is the fastest way to travel long distances.

The Air Scouts are participating in a camping trip this weekend.