when to use subj présent and subj passé while using jusqu'a ce que

Question

hi,when to use subj présent and subj passé while using jusqu'a ce que ?can you explain clearly in what situation they must be used?sorry i could not understand why to use subjonctif présent in certain case and passé in another cases?thankyou in advanceDona

Accepted Answer

Bonjour Dona, 
It's true. Understanding the use of the subjunctive is tricky. 
If we look at the example of 'kissing' - 'embrassés', the difference is that for the Subjonctif présent, the main clause action (kissing - 'embrassés') has continued until exactly to the point that the person’s wife has arrived (second action), e.g ‘she has opened the door and they have stopped instantly’ whereas for the Subjonctif Passé the main clause action ('kissing' - 'embrassés') has continued until after the wife has arrived, e.g ‘she has opened the door but they haven’t realised and kept kissing for an indefinite period of time’
The main clause action will go on until the action after jusqu’à ce que happens:

Nous nous sommes embrassés (main clause action)
         jusqu’à ce que sa femme arrive → they stopped instantly

the main clause action will go on until the action has happened and stopped:

Nous nous sommes embrassés (main clause action)
         jusqu’à ce que sa femme soit arrivée → they carried on kissing for a bit

I hope this is helpful. 
Bonne journée!