It's difficult to understand his explanation.

He increased the time spent together to deepen his relationship with her.

Cultural exchange between Japan and Korea is important for deepening understanding between the two countries.

There is a wonderful sumo arena in Ryogoku.

Exchanges between both countries are becoming more active.

The exchange with him broadened my horizons.

Interacting with him broadened my horizons.

Health is very important.

His opinion is very important.

It's difficult to understand his explanation.