or brush up on
If you brush up something or brush up on it, you practise it or improve your knowledge of it.
I had hoped to brush up my Spanish...
Eleanor spent much of the summer brushing up on her driving.
PHRASAL VERB : V P n (not pron) , V P P n
or brush up on
If you brush up something or brush up on it, you practise it or improve your knowledge of it.
I had hoped to brush up my Spanish...
Eleanor spent much of the summer brushing up on her driving.
PHRASAL VERB : V P n (not pron) , V P P n
Collins COBUILD Advanced Learner's English Dictionary. Английский словарь Коллинз COBUILD для изучающих язык на продвинутом уровне. 2006