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

These are the same as the relative pronouns, only they are written with an accent --

¿Quién,-es? (who, whom?)
¿Cuál,-es? (which?)
¿Qué? (what?)
¿Cúyo,-a,-os,-as? (whose?)
¿De quién,-es[103]? (whose?)
¿Cuánto,-a,-os,-as? (how much, how many?)

Footnote 103: "De quién" is more usual than "Cúyo" in interrogations.

Cuál when interrogative is used without the definite article which must accompany it when it is a relative pronoun. Quién, interrogative, is never an adjective.

EXAMPLES --

¿Quién vino a verme? Who came to see me?

¿Cuál arreglo le gusta á V. más? Which arrangement do you prefer?

¿Cúyo es este lápiz?         Whose is this pencil? or Whose
¿Cúyo lápiz es este?         pencil is this?
¿De quién es este lápiz?

¿De quién recibió V. la consignación de madera? From whom did you receive the consignment of timber?

¿A quiénes nos refieren Vs. para informes? To whom do you refer us for information?

¿Cuánto me cobrará V.? How much will you charge me?

Cuál (which) is often used instead of the English "what", as --

¿Cuáles son sus intenciones? What are your intentions?

Qué is used in exclamatory sentences -- "what a", as --

¡Qué lástima! What a pity! ¡Qué bonitos paños! What nice suitings![104]

Footnote 104: Before an adjective without a noun following "qué" translates the English "how": -- ¡Qué bonito! how nice!

An emphatic tan or más may be inserted, thus --

¡Qué paño tan bonito! What a very nice suiting! ¡Qué hombre más rico! What a very rich man!

Cuál is used in exclamatory clauses instead of cómo (how), as --

¡Cuál le han reducido las desgracias! How (or to what a state) misfortunes have reduced him! ¡Cuál la ví! How (or in what a state) did I see her!

Cuánto is also used in exclamations, as --

¡Cuánto le agradezco su amabilidad! How much obliged I am for your kindness!

Cual without article and without accent is used for "as," as --

Una casa (tal) cual yo la deseaba: A house (such) as I liked.

Such expressions as "He wrote me a letter, which letter I still possess," are translated "Me escribió una carta, cuya carta aun tengo."

Subjunctive Mood, Imperfect Tense (2nd form).

     Haber.                Tener.       Ser.        Estar.

 Que yo hubiera          Tuviera        Fuera        Estuviera
  "  tú hubieras         Tuvieras       Fueras       Estuvieras
  "  él hubiera          Tuviera        Fuera        Estuviera
  "  nosotros hubiéramos Tuviéramos     Fuéramos     Estuviéramos
  "  vosotros hubierais  Tuvierais      Fuerais      Estuvierais
  "  ellos hubieran      Tuvieran       Fueran       Estuvieran

Subjunctive Mood, Future Tense.

 Que yo hubiere (that    Tuviere (that  Fuere (that  Estuviere
     I shall have,        I shall have,  I shall be,  (that I shall
     etc.)                etc.)          etc.)        be, etc.)
  "  tú hubieres         Tuvieres       Fueres       Estuvieres
  "  él hubiere          Tuviere        Fuere        Estuviere
  "  nosotros hubiéremos Tuviéremos     Fuéremos     Estuviéremos
  "  vosotros hubiereis  Tuviereis      Fuereis      Estuviereis
  "  ellos hubieren      Tuvieren       Fueren       Estuvieren

Imperative Mood. (This mood is used to command or beg.)

 Hablar   Habla[105](speak thou, sing.)     Hablad (speak you, plu.)
 Temer    Teme      (fear    "        )     Temed  (fear   "       )
 Partir   Parte     (depart  "        )     Partid (depart "       )
 Haber    Hé[106]   (have    "        )     Habed  (have   "       )
 Tener    Ten       (  "     "        )     Tened  ( "     "       )
 Ser      Sé        (be      "        )     Sed    (be     "       )
 Estar    Está      ( "      "        )     Estad  ( "     "       )

Footnote 105: The Imperative Mood has only a separate form for the 2nd pers. sing. and plu. It has no 1st pers. sing. and the 1st pers. pl. and 3rd pers. sing. and pl. are taken from the Pres. Subj.

The 2nd pers. pl. is derived from the Infinitive Mood by changing the final r into d -- no exception.

The 2nd pers. sing. is the same as the 3rd pers. sing. of the Pres. Indicative, with a few exceptions (among which are Haber, Tener, Ser).

Footnote 106: Given as a form only, as Haber has no Imperative Mood in modern Spanish, except in Héme, héte, héle, aquí, etc. (here I am, here thou art, here he is, etc.), and in some other rare cases.

N.B. -- In Spanish there is no imperative negative, the Pres. Subj. negative being used instead, as --

Hablar.
No hables (do not (thou) speak).
No habléis (do not (you) speak).