In most cases, it is more a preservation of sounds that have been dropped elsewhere. But see https://en.wikipedia.org/wiki/Liaison_(French)#Liaison_on_inverted_

In most cases, it is more a preservation of sounds that have been dropped elsewhere. But see https://en.wikipedia.org/wiki/Liaison_(French)#Liaison_on_inverted_verbs https://en.wikipedia.org/wiki/Liaison_(French)#Liaison_on_in... , e.g. "parle-t-on", "a-t-il"