She has polycystic ovary syndrome.

He is writing a thesis on monotheism.

Sufficient caution is necessary when handling radioactive materials.

We are aiming to kill two birds with one stone with this plan.

The Atlantic puffin is one of the most commonly seen birds in the North Atlantic.

He was considered the wisest among the ignorant, like a bat in the land of the blind.

The Papua fire-eating bird, with its unique appearance, is a bird you won't forget once you see it.

He is exactly in the state of 'A frog in a well does not know the vast ocean.'

He spoke of his big dreams, saying, 'How can a sparrow understand the ambitions of a swan?'

General relativity is a theory of physics proposed by Einstein.