He is recovering from an illness, and has not fully recovered yet.

Something is moving in the darkness.

He became part of the dark side, and ended up fighting against his former comrades.

The park is beautiful at dusk.

When the evening twilight comes, the town becomes quiet.

He bought illegal goods on the black market.

He was searching for something in the darkness.

He overcame the darkness of his own heart.

Darkness covered his heart.

He was searching for something in the dark.