Je suis - when is the final 's' silent?

Question

With the above examples the final 's' in 'je suis a' is silent. But when saying 'Je suis aller..' I have heard the s pronounced? Is there a rule for when the final 's' is silent or not?

Accepted Answer

Hi Just For Fun, 
The liaisons after c'est/il est/suis/sont are what we call optional liaisons -
So you can say - Je suis //allé or Je suiZallé

C’est // évident  OR   C’esTévident ( It’s obvious)
Il est // impossible de vous tromper OR Il esTimpossible de ……( It’s impossible for you to make a mistake )
Il est // entré dans la chambre …OR Il esTentré dans la chambre... ( He came into the bedroom)
Ils sont // allés en France OR  Ils sonTallés en France ( They went to France)
Elle s’est // enfermée dans sa chambre OR  Elle s’esTenfermée dans sa chambre ( She locked herself in her bedroom)
Je suis // étudiant en Médecine OR Je suiZétudiant en Médecine ( I am a student of Medicine)
Quand il est // arrivé, nous sommes partis  OR QuanTil esTarrivé, nous sommes partis ( We left when he arrived)

Hope this helps!

Answer

Liaisons are somewhat complicated in French, as there are required, optional and forbidden liaisons. Here is a link that will help you further:https://www.lawlessfrench.com/pronunciation/liaisons/

Answer

Thanks for the replies. I understand better now.

Answer

I was reading the liaison lessons in the link provided, and one case has me confused. It says Comment__ is a forbidden liaison, but I clearly remember being taught in school, CommenTallez-vous? with liaison between the t and the a. Is this incorrect?