Present — what is happening now, and what happens habitually
| yo | abroI open | nosotros | abrimoswe open |
| tú | abresyou open | vosotros | abrísyou all open |
| él/ella/Ud. | abrehe/she opens | ellos/Uds. | abrenthey open |
Present perfect — have —ed; a past still touching now. Spain: today, this week. Latin America: mostly the indefinido instead
| yo | he abiertoI have opened | nosotros | hemos abiertowe have opened |
| tú | has abiertoyou have opened | vosotros | habéis abiertoyou all have opened |
| él/ella/Ud. | ha abiertohe/she has opened | ellos/Uds. | han abiertothey have opened |
Present subjunctive — after que with wishes, doubt, emotion, ojalá
| yo | abra(that) I open | nosotros | abramos(that) we open |
| tú | abras(that) you open | vosotros | abráis(that) you all open |
| él/ella/Ud. | abra(that) he/she opens | ellos/Uds. | abran(that) they open |
Present perfect subjunctive — have —ed, under doubt or emotion: no creo que haya venido
| yo | haya abierto(that) I have opened | nosotros | hayamos abierto(that) we have opened |
| tú | hayas abierto(that) you have opened | vosotros | hayáis abierto(that) you all have opened |
| él/ella/Ud. | haya abierto(that) he/she has opened | ellos/Uds. | hayan abierto(that) they have opened |
Preterite — a finished past action — it started, it ended
| yo | abríI opened | nosotros | abrimoswe opened |
| tú | abristeyou opened | vosotros | abristeisyou all opened |
| él/ella/Ud. | abrióhe/she opened | ellos/Uds. | abrieronthey opened |
Imperfect — used to / was —ing; background, habits, descriptions
| yo | abríaI used to open | nosotros | abríamoswe used to open |
| tú | abríasyou used to open | vosotros | abríaisyou all used to open |
| él/ella/Ud. | abríahe/she used to open | ellos/Uds. | abríanthey used to open |
Past perfect — had —ed; further back than another past event
| yo | había abiertoI had opened | nosotros | habíamos abiertowe had opened |
| tú | habías abiertoyou had opened | vosotros | habíais abiertoyou all had opened |
| él/ella/Ud. | había abiertohe/she had opened | ellos/Uds. | habían abiertothey had opened |
Imperfect subjunctive — si clauses and past-tense wishes: si tuviera, quería que fuera
| yo | abriera(that) I opened | nosotros | abriéramos(that) we opened |
| tú | abrieras(that) you opened | vosotros | abrierais(that) you all opened |
| él/ella/Ud. | abriera(that) he/she opened | ellos/Uds. | abrieran(that) they opened |
Imperfect subjunctive — the same tense, second form; commoner in Spain and in writing
| yo | abriese(that) I opened | nosotros | abriésemos(that) we opened |
| tú | abrieses(that) you opened | vosotros | abrieseis(that) you all opened |
| él/ella/Ud. | abriese(that) he/she opened | ellos/Uds. | abriesen(that) they opened |
Past perfect subjunctive — had —ed, hypothetically: si hubiera sabido
| yo | hubiera abierto(that) I had opened | nosotros | hubiéramos abierto(that) we had opened |
| tú | hubieras abierto(that) you had opened | vosotros | hubierais abierto(that) you all had opened |
| él/ella/Ud. | hubiera abierto(that) he/she had opened | ellos/Uds. | hubieran abierto(that) they had opened |
Preterite perfect — had —ed, immediately before; literary, all but extinct
| yo | hube abiertoI had opened | nosotros | hubimos abiertowe had opened |
| tú | hubiste abiertoyou had opened | vosotros | hubisteis abiertoyou all had opened |
| él/ella/Ud. | hubo abiertohe/she had opened | ellos/Uds. | hubieron abiertothey had opened |
Future — will — (spoken Spanish often prefers voy a + infinitivo)
| yo | abriréI will open | nosotros | abriremoswe will open |
| tú | abrirásyou will open | vosotros | abriréisyou all will open |
| él/ella/Ud. | abriráhe/she will open | ellos/Uds. | abriránthey will open |
Conditional — would —; also softens a request into politeness
| yo | abriríaI would open | nosotros | abriríamoswe would open |
| tú | abriríasyou would open | vosotros | abriríaisyou all would open |
| él/ella/Ud. | abriríahe/she would open | ellos/Uds. | abriríanthey would open |
Future perfect — will have —ed; done by some future point
| yo | habré abiertoI will have opened | nosotros | habremos abiertowe will have opened |
| tú | habrás abiertoyou will have opened | vosotros | habréis abiertoyou all will have opened |
| él/ella/Ud. | habrá abiertohe/she will have opened | ellos/Uds. | habrán abiertothey will have opened |
Conditional perfect — would have —ed; the road not taken
| yo | habría abiertoI would have opened | nosotros | habríamos abiertowe would have opened |
| tú | habrías abiertoyou would have opened | vosotros | habríais abiertoyou all would have opened |
| él/ella/Ud. | habría abiertohe/she would have opened | ellos/Uds. | habrían abiertothey would have opened |
Future subjunctive — legal and proverbial only: adonde fueres, haz lo que vieres
| yo | abriere(should) I open | nosotros | abriéremos(should) we open |
| tú | abrieres(should) you open | vosotros | abriereis(should) you all open |
| él/ella/Ud. | abriere(should) he/she open | ellos/Uds. | abrieren(should) they open |
Imperative (do it) — orders and requests; there is no yo form
| yo | — | nosotros | abramoslet's open |
| tú | abreopen! | vosotros | abridopen! |
| él/ella/Ud. | abraopen! | ellos/Uds. | abranopen! |
Imperative (don't) — no + subjunctive — never the affirmative form with no in front
| yo | — | nosotros | no abramoslet's not open |
| tú | no abrasdon't open | vosotros | no abráisdon't open |
| él/ella/Ud. | no abradon't open | ellos/Uds. | no abrandon't open |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.
I — the speaker
| Presente | abroI open |
| Perfecto | he abiertoI have opened |
| Subj. presente | abra(that) I open |
| Subj. perfecto | haya abierto(that) I have opened |
| Futuro | abriréI will open |
| Condicional | abriríaI would open |
| Fut. perfecto | habré abiertoI will have opened |
| Cond. perfecto | habría abiertoI would have opened |
| Subj. futuro | abriere(should) I open |
| Indefinido | abríI opened |
| Imperfecto | abríaI used to open |
| Pluscuamp. | había abiertoI had opened |
| Subj. imperf. | abriera(that) I opened |
| Subj. -se | abriese(that) I opened |
| Subj. pluscuamp. | hubiera abierto(that) I had opened |
| Pret. anterior | hube abiertoI had opened |
| Imperativo | — |
| Imper. negativo | — |
we — the speaker plus others
| Presente | abrimoswe open |
| Perfecto | hemos abiertowe have opened |
| Subj. presente | abramos(that) we open |
| Subj. perfecto | hayamos abierto(that) we have opened |
| Futuro | abriremoswe will open |
| Condicional | abriríamoswe would open |
| Fut. perfecto | habremos abiertowe will have opened |
| Cond. perfecto | habríamos abiertowe would have opened |
| Subj. futuro | abriéremos(should) we open |
| Indefinido | abrimoswe opened |
| Imperfecto | abríamoswe used to open |
| Pluscuamp. | habíamos abiertowe had opened |
| Subj. imperf. | abriéramos(that) we opened |
| Subj. -se | abriésemos(that) we opened |
| Subj. pluscuamp. | hubiéramos abierto(that) we had opened |
| Pret. anterior | hubimos abiertowe had opened |
| Imperativo | abramoslet's open |
| Imper. negativo | no abramoslet's not open |
you (informal) — one person you are familiar with
| Presente | abresyou open |
| Perfecto | has abiertoyou have opened |
| Subj. presente | abras(that) you open |
| Subj. perfecto | hayas abierto(that) you have opened |
| Futuro | abrirásyou will open |
| Condicional | abriríasyou would open |
| Fut. perfecto | habrás abiertoyou will have opened |
| Cond. perfecto | habrías abiertoyou would have opened |
| Subj. futuro | abrieres(should) you open |
| Indefinido | abristeyou opened |
| Imperfecto | abríasyou used to open |
| Pluscuamp. | habías abiertoyou had opened |
| Subj. imperf. | abrieras(that) you opened |
| Subj. -se | abrieses(that) you opened |
| Subj. pluscuamp. | hubieras abierto(that) you had opened |
| Pret. anterior | hubiste abiertoyou had opened |
| Imperativo | abreopen! |
| Imper. negativo | no abrasdon't open |
you all — informal plural, Spain only
| Presente | abrísyou all open |
| Perfecto | habéis abiertoyou all have opened |
| Subj. presente | abráis(that) you all open |
| Subj. perfecto | hayáis abierto(that) you all have opened |
| Futuro | abriréisyou all will open |
| Condicional | abriríaisyou all would open |
| Fut. perfecto | habréis abiertoyou all will have opened |
| Cond. perfecto | habríais abiertoyou all would have opened |
| Subj. futuro | abriereis(should) you all open |
| Indefinido | abristeisyou all opened |
| Imperfecto | abríaisyou all used to open |
| Pluscuamp. | habíais abiertoyou all had opened |
| Subj. imperf. | abrierais(that) you all opened |
| Subj. -se | abrieseis(that) you all opened |
| Subj. pluscuamp. | hubierais abierto(that) you all had opened |
| Pret. anterior | hubisteis abiertoyou all had opened |
| Imperativo | abridopen! |
| Imper. negativo | no abráisdon't open |
he, she, you (formal) — one other person — formal you shares it
| Presente | abrehe/she opens |
| Perfecto | ha abiertohe/she has opened |
| Subj. presente | abra(that) he/she opens |
| Subj. perfecto | haya abierto(that) he/she has opened |
| Futuro | abriráhe/she will open |
| Condicional | abriríahe/she would open |
| Fut. perfecto | habrá abiertohe/she will have opened |
| Cond. perfecto | habría abiertohe/she would have opened |
| Subj. futuro | abriere(should) he/she open |
| Indefinido | abrióhe/she opened |
| Imperfecto | abríahe/she used to open |
| Pluscuamp. | había abiertohe/she had opened |
| Subj. imperf. | abriera(that) he/she opened |
| Subj. -se | abriese(that) he/she opened |
| Subj. pluscuamp. | hubiera abierto(that) he/she had opened |
| Pret. anterior | hubo abiertohe/she had opened |
| Imperativo | abraopen! |
| Imper. negativo | no abradon't open |
they, you all — several others — plural you shares it
| Presente | abrenthey open |
| Perfecto | han abiertothey have opened |
| Subj. presente | abran(that) they open |
| Subj. perfecto | hayan abierto(that) they have opened |
| Futuro | abriránthey will open |
| Condicional | abriríanthey would open |
| Fut. perfecto | habrán abiertothey will have opened |
| Cond. perfecto | habrían abiertothey would have opened |
| Subj. futuro | abrieren(should) they open |
| Indefinido | abrieronthey opened |
| Imperfecto | abríanthey used to open |
| Pluscuamp. | habían abiertothey had opened |
| Subj. imperf. | abrieran(that) they opened |
| Subj. -se | abriesen(that) they opened |
| Subj. pluscuamp. | hubieran abierto(that) they had opened |
| Pret. anterior | hubieron abiertothey had opened |
| Imperativo | abranopen! |
| Imper. negativo | no abrandon't open |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.