The Nominative Case should be used:
1. When the noun or pronoun is the subject of a finite verb; that is, a verb other than an infinitive. See 3 under Objective Case.
2. When it is an attribute complement. An attribute complement, as explained in Chapter I, is a word used in the predicate explaining or stating something about the subject. Examples: It is I, The man was he, The people were they of whom we spoke.
3. When it is used without relation to any other part of speech, as in direct address or exclamation.
The Objective Case should be used:
1. When the noun or pronoun is the object of a verb; as, He named me, She deceived them, They watch us.
2. When it is the object of a preposition, expressed or understood: as, He spoke of me, For whom do you take me, He told (to) me a story.
3. When it is the subject of an infinitive; as, I told him to go, I desire her to hope. The infinitives are the parts of the verb preceded by to; as, to go, to see, to be, to have been seen, etc. The sign of the infinitive, to, is not always expressed. The objective case is, nevertheless, used; as, Let him (to) go, Have her (to be) told about it.
4. When it is an attribute complement of an expressed subject of the infinitive to be; as, They believed her to be me, He denied it to have been him. (See Note 2 below.)
The Possessive Case should be used: