He is an expert in entomology, especially knowledgeable about butterflies.

Insects are an important part of the natural world.

He is world-famous as an entomologist.

I stayed up late every night and ended up ruining my health.

He prayed to the heavens.

Ancient people looked up at the sky and observed the movement of the stars.

Ancient people looked up at the sky and observed the movement of the stars.

When I looked up at the sky, a beautiful blue sky was spread out.

The sky is blue, and the weather is nice, isn't it?

The pyralid was flying, spreading its beautiful wings.