Why can you use relative clauses with implicit complementisers or relative pronouns?
Why are these correct?
The work I am doing is easy.
The house he lives at.
The book I am writing is about different realms.
The man I was helping thanked me.
The ant I was blocking the road of.
The school I go to.
Shouldn't "I am doing", "lives at", "writing", "was helping", "blocking", and "go" be at the front? Could you please explain the grammar here? Thank you.
Simply, the relative pronoun "that" has been omitted.
The work that I am doing is easy.
The house that he lives at
The book that I am writing is about different realms.
The man that/who I was helping thanked me.
The ant that I was blocking the road of
The school that I go to
Such clauses are, as @legatrix comments, called reduced relative clauses, wherein the complementiser or relative pronoun is implicit.