formation
The past subjunctive resembles the passé composé in that it is formed with the present subjunctive of the appropriate auxiliary verb
(avoir or être) and the past participle of the main verb.
rire'to laugh'
que j'aie ri
que nous ayons ri
que tu aies ri
que vous ayez ri
qu'il / elle / on ait ri
qu'ils / elles aient ri
sortir'to go out'
que je sois sorti(e)
que nous soyons sorti(e)s
que tu sois sorti(e)
que vous soyez sorti(e)(s)
qu'il / elle / on soit sorti(e)
qu'ils / elles soient sorti(e)s
uses
The past subjunctive is normally used in dependent clauses that describe an action which precedes the action of the main clause.
The past subjunctive is introduced by the same kinds of clauses that introduce the present subjunctive
(See subjunctive of obligation, doubt, will, emotion, desire and conjunctions that take the subjunctive).
Note the past tense meaning of the event encoded in the past subjunctive.
The present subjunctive, on the other hand, indicates a simultaneous action or a future action.
Compare these sentences (present subjunctive in orange, past subjunctive in blue):
Tammy: Je suis surprise que tu écrives ce livre.
Tammy: I am surprised that you are writing this book.
Tex: Je suis surpris que tu aies lu ce livre.
Tex: I am surprised that you have read this book.
Tammy: J'ai été surprise que tu écrives ce livre.
Tammy: I was surprised that you were writing this book.
Tex: J'ai été surpris que tu aies lu ce livre.
Tex: I was surprised that you had read this book.
Note that the tense of the verb in the main clause in French does not predict the tense of the subjunctive in the dependent clause.
The choice between the present and past subjunctives depends on the chronological relationship between the two clauses.
Listen to the following dialogue.
Tammy: Tex est content que la France ait gagné la Coupe du Monde en 98.
Tammy: Tex is happy that France won the 1998 World Cup.
Mais je doute qu'il soit sorti après la finale parce qu'il avait trop bu.
But, I doubt that he went out after the final game because he had drunk too much.
Ma mère n'était pas sûre que Tex ait aimé le vin qu'elle avait envoyé.
My mom wasn't sure that Tex had liked the wine that she sent for the game.
Mais j'ai peur que Tex et Edouard l'aient trop aimé!
But, I'm afraid that Tex and Edouard liked it too well!
