The relative pronoun can be deleted if there
is a new subject and verb following it:
A. This is the house
that Jack built.
B. This is the house Jack built.
A. The person
whom you see
is my father.
B. The person you see is my father.
A. This is the place
where I live.
B. This is the place I live.
A. I don't know the
reason
why she is late.
B. I don't know the reason she is late
(Also : I don't know why she is late. )
A. The woman
whom he likes
is married.
B. The woman he likes is married.
Notes:
Do not delete a relative pronoun that is followed by
a verb other than be:
The man
who likes lasagna
is my father.
X The man likes lasagna is my father.
Never delete the
relative pronoun
whose:
The man
whose car broke down
went to the station.
X The man car broke down went to the station.