He is connected to a ventilator due to his severe condition.

Alkynes play an important role in organic chemistry.

Alkenes play an important role in organic chemistry.

Alkenes play an important role in organic chemistry.

Alkanes are basic components of organic chemistry.

He is studying the history of African Americans.

The parasympathetic nervous system helps our body to relax and conserve energy.

Zen is a festival ceremony performed by the Chinese emperor.

Through the practice of Zen, I gained peace of mind.

She repaired my jeans using the darning technique.