in
( BrE ) (in the past) to prepare the engine of a new car for normal use by driving slowly and carefully :
( figurative )
Whatever system you choose, it must be run in properly.
in
( BrE ) (in the past) to prepare the engine of a new car for normal use by driving slowly and carefully :
( figurative )
Whatever system you choose, it must be run in properly.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005