- Wrong: They are as old as us.
- Right: They are as old as we [are].
- Wrong: He is taller than her.
- Right: He is taller than she [is].
[Note.]—Than and as are conjunctions, not prepositions. When they are followed by a pronoun merely, this pronoun is not their object, but part of a clause the rest of which may be understood. The case of this pronoun is determined by its relation to the rest of the unexpressed clause. Sometimes the understood clause calls for the objective: "I like his brother better than [I like] him." Than whom, though ungrammatical, is sanctioned by usage.
[b.] Guard against the improper attraction of who into the objective case by intervening expressions like he says.
- Wrong: The man whom they believed was the cause of the trouble left the country. [They believed is parenthetical, and the subject of was is who.]
- Right: The man who they believed was the cause of the trouble left the country.
- Wrong: Whom do you suppose made us a visit?
- Right: Who do you suppose made us a visit?
Guard against the improper attraction of who or whoever into the objective case by a preceding verb or preposition.
- Wrong: Punish whomever is guilty. [The pronoun is the subject of is. The object of punish is the entire clause whoever is guilty.]
- Right: Punish whoever is guilty.
- Wrong: The mystery as to whom had rendered him this service remained. [The pronoun is the subject of had rendered. The object of the preposition is the entire clause who had rendered him this service.]
- Right: The mystery as to who had rendered him this service remained.
[c.] The predicate complement of the verb to be (in any of its forms, is, was, were, be, etc.) is in the nominative case. To be never takes an object, because it does not express action.
- Wrong: Was it her? Was it them? It is me.
- Right: Was it she? Was it they? Is it I.
- Wrong: The happiest people there were him and his mother.
- Right: The happiest people there were he and his mother.
[d.] The object of a preposition or a verb is in the objective case.
- Wrong: Some of we fellows went fishing.
- Right: Some of us fellows went fishing.
- Wrong: That seems incredible to you and I.
- Right: That seems incredible to you and me.
- Wrong: Who did they detect?
- Right: Whom did they detect?