When I was working relative clauses, I was encountered by a footnote, and it sounds me weird.
FootNote: The objects or subjects described by relative clauses cannot take demonstrative pronouns or adjectives.
example: This theatre which exhibits the boring life of a rich man is very expensive.
Continue of footnote: The demonstrative pronoun "this" cannot be used if the noun is described with a relative clause. Instead of the word "this", the article "the" must be used.
Is it really true ?
why cannot we use "this" ?