اعراب : هذا البيت مفتوح بابه

This sentence is parsed as follows: “This: a demonstrative noun acting as the subject. The house: a substitute for the subject, with a visible fatha indicating its nominative case. Open: a predicate with a fatha indicating its nominative case. Its door: a deputy for the object of the verb (open), with a fatha indicating its nominative case. And the pronoun “its” is a pronoun in the genitive case.”