Pitman's Commercial Spanish Grammar (2nd ed.)

A Possessive Adjective accompanies a noun; a Possessive pronoun stands for a noun.

The Possessive Adjectives are --

 Mi (m. & f., sing.)       my
 Mis (m. & f., plu.)       my
 Tu (m. & f., sing.)       thy
 Tus (m. & f., plu.)       thy
 Su (m. & f., sing.)       his, her, its, one's, their,
                            your, (polite)
 Sus (m. & f., plu.)       his, her, its, one's, their,
                            your, (polite)
 Nuestro-a, os-a           our
 Vuestro-a, os-as          your (familiar)

EXAMPLES --

Mi embarque: My shipment.
Nuestro arreglo: Our arrangement.
Su sinceridad: His, her, or their sincerity.
Tu beneficio: Thy benefit.
Sus fondos: His funds, capital.

De él, de ella, de ellos, de V., etc., may be added for the sake of clearness, but are not needed when the sense is clear without them.[88]

In the 3rd person (but not in the 1st and 2nd) instead of "su ... de él," "su ... de V.," etc., we may say "el ... de él," "el ... de V.," etc.

Footnote 88: "De V." is added also for politeness ("V." being a title in itself -- your grace).

The Possessive Pronouns are --

El mío, la mía, los míos, las mías (mine).
El tuyo, la tuya, los tuyos, las tuyas (thine).
El suyo, la suya, los suyos, las suyas (his, hers, theirs, yours, polite).
El nuestro, la nuestra, los nuestros, las nuestras (ours).
El vuestro, la vuestra, los vuestros, las vuestras (yours familiar).

The Possessive Pronoun must be preceded by the definite article except when it follows the verb "to be" ("Ser") and ownership is asserted.

EXAMPLES --

Su casa es más importante que la mía: His firm is more important than mine.

V. ha acabado su trabajo, pero yo no he principiado el mío: You have finished your work, but I have not started mine.

Estos títulos y acciones son míos: These bonds and shares are mine (viz., belong to me).[89]

Footnote 89: If the intention is only to distinguish between one object and another the article is maintained; as, Estas son mis acciones, aquellas son las de V. (these are my shares, those are yours).

Possessive Adjectives Emphatic. If any emphasis is placed on the possessive adjectives, the forms of the possessive pronouns are used, following the noun, as --

Quiero la maleta mía y no la de su amigo: I want my portmanteau, not your friend's.

"A friend of mine," "a customer of yours" will be translated "un amigo de los míos," "un cliente de los suyos," or also "un amigo mío," "un cliente suyo," without the preposition de.

The Possessive Pronoun preceded by the neuter article lo denotes "property in general," as --

Lo mío (mine -- that which is mine).
Lo nuestro (ours -- that which belongs to us).
Lo suyo or lo propio (one's own property).
Lo ajeno (other people's property (that which belongs to others)).

In addressing a person translate "my," etc., by "mío," etc., as --

Amigo mío: My friend.
Muy Señor mío (usual introduction to a Spanish letter).

But if the noun is qualified by an adjective, both "mi" and "mío" are used ("mi" is more general), as Mi querido amigo (my dear friend).

 Subjunctive Mood, Imperfect Tense (2nd Form).[90]

 Hablar.                   Temer.              Partir.

 Que yo hablara            Temiera             Partiera
  "  tu hablaras           Temieras            Partieras

  "  el hablara            Temiera             Partiéramos
  "  nosotros habláramos   Temiéramos          Partierais
  "  vosotros hablarais    Temierais           Partieran
  "  ellos-as hablaran     Temieran

Footnote 90: Used just the same as the 1st form; but it may also be used instead of the Conditional Mood.

 Subjunctive Mood, Future Tense.[91]

 Que yo hablare (that I    Temiere (that I     Partiere (that I
     shall speak, etc.)     shall fear, etc.)   shall depart, etc.)
  "  tú hablares           Temieres            Partieres
  "  él hablare            Temiere             Partiere
  "  nosotros habláremos   Temiéremos          Partiéremos
  "  vosotros hablareis    Temiereis           Partiereis
  "  ellos-as hablaren     Temieren            Partieren

Footnote 91: Refers to a future doubtful action; little used. Its place is generally supplied by the Present Subjunctive, and, after si (if), by the Present Indicative.