1. Imperfect subjunctive
Putting together the uses

2. Formation review Passé simple stem + endings
Er - asse, asses, at, assions, assiez, assent
Ir- isse, isses, it, issions, issiez, issent
Re - usse, usses, ut, ussions, ussiez, ussent

3. Irregulars Etre - fu stem + re verb endings
Faire - fi stem + ir verb endings
Avoir - eu stem + re verb endings

4. So we have a general idea how to form and use the imperfect subjunctive
Let's put them together

5. "Concordance du temps" - what you do to one side, you do to the other
If you have an expression of doubt, relative clauses, volition, emotion, or academic expressions
After your que goes the subjunctive

6. What is NEVER subjunctive?
Penser
Trouver
Croire
Etre sur que

7. But when you try and say its already happened, your first half might need to be imperfect
Il faut que becomes il fallait que
Je veux que becomes je voulais que
Il doute que becomes il doutait que
Je cherche quelqu'un qui becomes je cherchais quelqu'un qui
Tu aimes que becomes tu aimais que

8. So wait, if I am talking about what happened, does it go to past or imperfect?
Imperfect: emotion, details, what was going on, no definite time
Past: one definitive time. This is pretty rare.
Things like 'il a fallu que il ait regarde.'
'It was (at one point in time) necessary that he saw (one point in time)

9. What does this look like with academic?
Il allait pour que Elle quittat