La règle · The rule
Fifteen books of written practice have given you an ordered map of the language and hundreds of hours of the one thing that is hard to arrange alone: correction. Every answer you checked was checked against a printed key.
Et aussi · And also
What they have NOT given you is an ear, and no book can. That comes from listening and from speaking with people who will not slow down for you — and you are now equipped to start.
Attention · Watch out
l'oreille exercée is the trained ear, and no book gives it: that comes from people who will not slow down for you (ralentir). équipé agrees like any participle: équipé, équipée — you are equipped for that, not finished with it.