The word 'serious' is an adjective, used to describe a noun, or as the object of a linking verb as a predicate adjective. Example sentences:
Fraud is a serious criminal offence.
All jape aside, death is a really serious subject. Richard is known to jape when he doesn't have a proper answer.
The verb in the sentence is: isThe verb 'is' is functioning as a linking verb, the object of the verb restates the subject (whiz = he).
consequently, you can no longer eat spinach.
Children have such a resiliency, even when suffering from a serious illness.
Fraud is a serious criminal offence.
Overgrazing has caused serious degeneration of grassland.
the judge explained that because his offence was so serious,his prison sentence was protracted.
He has a serious mental disorder.
I was sure the the principal would summon me for a serious talk after what I did.
Habitual lying is a serious weakness in a person's character.
The criminal was convicted of robbery and sentenced to prison for ten years.
You are a serious contender for the Dumbest Question Ever Award.
Life is hard for me because I have many serious neuroses.
This is a very serious accusation.He was involved in a serious collision.She wasn't very serious.I shot him a serious glare from across the room.
the lady was really serious
some of the serious accidents are due to unguarded stairway floor openings.