to speak at length about a topic
parler longuement d'un sujet (parler longuement d'un sujet)
"He loved to hold forth on travel stories."
"Il adorait parler longuement d'un sujet sur les histoires de voyage." (Il adorait parler longuement d'un sujet sur les histoires de voyage.)
to talk about something that has been worrying you
to impress or amaze someone greatly
to risk everything on a single venture or decision
a simple and perfect solution to a complex problem
To prepare for future work or success.
to reserve something for a particular purpose