... back of one's hand了如指掌； constant dropping wears the stone 滴水穿石； fish in troubled water 混水摸鱼； ...
权威例句
1.
Carwyn Jones will welcome the money but inevitably remind the UK government that it's giving back with one hand a little bit of the far bigger sum it's already taken with the other.
BBC: Stimulus - the Welsh, Scottish and Westminster way