concentration on sth的用法和樣例：
例句
- She couldn't concentrate on a book very long.
她不能長(cháng)時(shí)間專(zhuān)心讀一本書(shū)。 - You must keep your mind on your work.
你必須專(zhuān)心工作。 - I can't concentrate on my work when I'm tired.
我累了就無(wú)法集中精力工作。 - You must focus on turning negatives into positives.
你必須集中精力將消極的東西變成積極的東西。
