In this lake, denitrification is actively taking place.

This soil is active in denitrification, releasing nitrogen into the atmosphere.

This festival is held every year.

His activity surprised all of us.

She is a very active person.

He almost died of suffocation, but fortunately he was saved.

He took off his shirt.

We had a picnic at the lake over the weekend.

We went for a picnic to the lake on the weekend.