1、concentration
全神贯注;专心;专注
Neal kept interrupting, breaking my concentration.
尼尔不停地打断我，使得我无法集中注意力。
We lacked concentration and it cost us the goal and the game.
我们注意力不够集中，结果丢了球，输了比赛。
集中;汇集
The area has one of the world's greatest concentrations of wildlife.
这个地区是世界上野生动物最为密集的区域之一。
There's been too much concentration of power in the hands of central authorities.
权力一直过多地集中在中央机构手中。
浓度
pH is a measure of the concentration of free hydrogen atoms in a solution.
pH值是测试溶液中自由氢原子浓度的单位。
The latest data showed that global ozone concentrations had dropped several per cent over the last decade.
最新数据显示，过去10年来全球臭氧的浓度降低了几个百分点。

2、back up
支持，证实（某种说法）
Radio signals received from the galaxy's centre back up the black hole theory.
从该星系中心收到的无线电信号证实了黑洞理论。
Her views are backed up by a 1989 Home Office report on crime.
1989年内政部的一份犯罪报告印证了她的观点。
备份（文件）
Make a point of backing up your files at regular intervals.
一定要定期备份文件。
I get so annoyed when I lose work because I've forgotten to back it up.
当我因为忘了备份把完成的工作弄丢时，真是懊恼极了。
将…付诸实施
The Secretary General says the declaration must now be backed up by concrete and effective actions.
秘书长说现在必须将宣言付诸具体有效的行动。
It is time the Government backed up its advert campaigns with tougher measures.
是政府采取更严厉的措施来兑现其宣传承诺的时候了。