The sympathetic nervous system controls the body's stress response.

He is a person of strong vanity who reads self-improvement books.

He decided to start a manual labor job.

She always says 'the lady doth protest too much,' seeming to deny his actions, but in reality, she loves him very much.

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.