He was demoted from department manager to section manager.

He always goes fishing on weekends.

He enjoys fishing in the lake every weekend.

The development of fusion reactors could potentially be the key to solving future energy problems.

Cold fusion is a part of physics and is a phenomenon that is not yet fully understood.

Research on cold fusion is still controversial.

He is hiding a secret.

My dream is to visit Scotland someday.

The prepositional case plays an important role in English grammar.

The river water is gurgling down.