The river water is flowing in the opposite direction.

This problem has a paradoxical answer.

He was prepared for the enemy's counterattack.

He began to strike back against the enemy.

He was plotting a rebellion against the king.

He outsmarted his competitors by using a contrarian business strategy.

He succeeded in business by going against the grain.

He is the type of person who 'breaks the stone bridge by tapping on it', so he is too careful and does not make progress.

He is good at playing the piano.

He is good at playing the piano.