section 3.3 of the syntax of french says that à and de at least in some cases aren’t prepositions, but rather DP*-internal inherent-case markers. (sorry I am not expert in linguistics to explain what the book says and French does not have a Descriptive grammar for non experts.)

section 3.3 of the syntax of french says that "à" and "de" at least in some cases aren’t prepositions, but rather DP*-internal inherent-case markers. (sorry I am not expert in linguistics for explain what the book says and French does not have a Descriptive grammar for non experts.)