podría, a lo mejor, quizás: expressing possibility and past ability
English "could" hides two different Spanish past tenses. For general past ability, use the imperfect podía; for managing to do something on one occasion, use the preterite pude.
De niño podía correr muy rápido. (As a child I could run very fast — general ability.)
Por fin pude abrir la puerta. (I finally managed to open the door — one occasion.)
Rule of thumb: could = podía; managed to / succeeded in = pude.
For polite suggestions and future possibility, Spanish uses the conditional podría — exactly like English "could/might".
Podríamos ir al cine esta noche. (We could go to the cinema tonight.)
¿Podrías ayudarme con esto? (Could you help me with this?)
Podría llover mañana. (It might rain tomorrow.)
Conjugation is regular: podría, podrías, podría, podríamos, podríais, podrían.
The everyday way to say "maybe" is a lo mejor — and the good news for learners is that it always takes the ordinary indicative, never the subjunctive.
A lo mejor voy mañana. (Maybe I will go tomorrow.)
A lo mejor está enfermo. (Maybe he is ill.)
In conversation, a lo mejor is the safest "maybe" — no special verb forms needed.
Quizás (or quizá) and tal vez also mean "maybe", but they usually take the subjunctive when the doubt is real.
Quizás venga más tarde. (Maybe he will come later — venga = subjunctive of venir.)
Tal vez sea verdad. (Maybe it is true — sea = subjunctive of ser.)
With the indicative (quizás viene) the speaker sounds more certain. At B1, learn the pattern quizás + subjunctive.
A very common B1 structure: puede que + subjunctive = "it may be that / might".
Puede que llegue tarde. (I might arrive late.)
Puede que no lo sepan. (They might not know.)
Your possibility toolkit: a lo mejor + indicative · quizás / tal vez + subjunctive · puede que + subjunctive · podría + infinitive.
Traps for English speakers
These are the errors English speakers make most often.