brush up

To refresh one's memory.

重溫，再練

To renew a skill.

更新技術，改善

brush someone back

(Baseball, informal)(of a pitcher) force a batter to step back to avoid being hit by a ball pitched close to the body

(棒球 非正式)（投球手）迫使擊球手后退以免被投出的近身球擊中

brush up on (或 brush something up)

improve one's previously good knowledge of or skill at a particular thing

溫習，復習

brush up on your telephone skills.

溫習一下你給人打電話的技巧。