Learn Spanish (Latin America): Quería que el alcalde reparara los baches en mi calle. - I wanted the mayor to repair the potholes in my street.

To build the imperfect subjunctive, you start with the "they" form of the past tense (the preterite). For reparar, that is repararon. Drop the -ron at the end, which leaves you with the base repara-. Then, add the subjunctive ending. Since the subject of this verb is the mayor (el alcalde, which is "he"), we add the ending -ra, giving us reparara.

Why is the second verb in the past subjunctive (reparara) instead of a normal past tense like reparó?

The first verb, Quería (I wanted), expresses a wish or desire. Just like in the present tense (where a phrase like "I want you to..." triggers the present subjunctive), expressing a wish or request in the past triggers the past (imperfect) subjunctive for the second verb.

The English translation says "to repair". Why doesn't Spanish just use the infinitive reparar here?

In English, we use the structure "I wanted [someone] to do [something]." However, in Spanish, when the person doing the wanting (I) is different from the person doing the action (the mayor), you cannot use an infinitive. You must use que plus a conjugated subjunctive verb. Literally, you are saying "I wanted that the mayor repair..."

I've seen some imperfect subjunctive verbs with accent marks. Why doesn't reparara have one?