Noun Clauses
John made a mistake.
Whoever said that made a mistake.
Whoever said that made a mistake.
- Whoever said that acts as the subject of the sentence.
I like pizza.
I like what you made.
I like what you made.
- What you made acts as the object in replace of pizza.
Let's talk about this.
Let's talk about what you did.
Let's talk about what you did.
- What you did replaces the object of the preposition.
I have become what I feared most.
- What I feared most is the noun predicate following the linking verb have become.