Alkenes, also known as olefin hydrocarbons, play an important role in organic chemistry.

Alkenes play a very important role in organic chemistry.

He was arrested for obstruction of public duties.

He is facing many difficulties due to gender identity disorder.

He is receiving treatment for obsessive-compulsive disorder.

His father fell into a persistent vegetative state due to a traffic accident.

He is not an ordinary human.

He planed the wood and made a model airplane.

He couldn't hide his jealousy towards her success.

He picked up the whip and started practicing.