Imperfect subjunctive and sequence of tenses

Form: take the 3rd person plural of the indefinido, drop -ron and add -ra, -ras, -ra, -ramos, -rais, -ran (accent in nosotros). So every irregularity of the indefinido carries over:

There is also a form in -se (hablase, tuviese) with the same meaning, more common in writing.

Uses

• The same triggers as the present subjunctive, when the main verb is in the past or conditional: Quería que vinieras. — I wanted you to come. Me pidió que lo ayudara. — He asked me to help him.
• Unreal if-clauses (see next section).
• como si, always: Habla como si lo supiera todo. — He talks as if he knew everything.
• ojalá + imperfect = unlikely wish: Ojalá tuviera más tiempo. — I wish I had more time.
• Politeness: Quisiera un café. — I'd like a coffee.

Pluperfect: hubiera + participle: Ojalá lo hubiera sabido. — If only I had known.