B-34：brush up 复习
A: What are you doing these days?
A: 你最近在忙什么？
B: I'm brushing up my Japanese.
B：我正在复习日语。
A: Reviewing your Japanese? What for?
A：复习日语？为什么？
B: I'm preparing for the entrance examination of post graduates.
B：我准备考研。
