I am studying Japanese.

Their relationship is codependent, they depend on each other.

He and I share a lot of things.

She can speak both languages fluently.

He learned about the concept of synergism in theology class.

The coexistence of humans and nature is important for the sustainability of the Earth.

Humans and nature should coexist.

He has a rare synaesthesia where he hears sounds when he sees colors.

Their opinions have many common points.

All of these points are on the same line.