brush up(on)
1.review (a skill,knowledge)one has learned in the past 重新学习;复习
I'll have to brush up my English before I go abroad.出国前我要温习一下英语。
He said he had to brush up on his history before the examination.他说他得在考试前复习历史。
2.make clean or bright with a brush 刷净;擦亮
Your boots should be brushed up a bit.你的长统靴该搽搽亮。