In a sentence where the main proposition is in the present or future tense of the indicative, the past tense of the subjunctive in the subordinate is used to remain consistent with the concordance of the tenses and thus express an event before the one stated in the main.
Je ne pense pas qu'il ait terminé à temps.
Je regretterai que mes amis soient restés chez eux.
In order to form the past tense of the subjunctive, it is necessary to know how to conjugate the auxiliaries "avoir" and "être" in the present tense of the subjunctive and how to form the past participle. The main difficulty of the past tense of the subjunctive comes from the agreements with the past participle.
Here is an example of a verb conjugated in the past tense of the subjunctive with the auxiliaries "avoir" and "être":
Subject | Auxiliary (avoir) | Past participle (finir) |
---|---|---|
que j' | aie | fini |
que tu | aies | fini |
qu'il | ait | fini |
que nous | ayons | fini |
que vous | ayez | fini |
qu'ils | aient | fini |
Subject | Auxiliary (être) | Past participle (venir) |
---|---|---|
que je | sois | venu |
que tu | sois | venu |
qu'l | soit | venu |
que nous | soyons | venus |
que vous | soyez | venus |
qu'ils | soient | venus |