1、concentration
全神貫注;專心;專注
Neal kept interrupting, breaking my concentration.
尼爾不停地打斷我，使得我無法集中注意力。
We lacked concentration and it cost us the goal and the game.
我們注意力不夠集中，結果丟了球，輸了比賽。
集中;匯集
The area has one of the world's greatest concentrations of wildlife.
這個地區是世界上野生動物最為密集的區域之一。
There's been too much concentration of power in the hands of central authorities.
權力一直過多地集中在中央機構手中。
濃度
pH is a measure of the concentration of free hydrogen atoms in a solution.
pH值是測試溶液中自由氫原子濃度的單位。
The latest data showed that global ozone concentrations had dropped several per cent over the last decade.
最新數據顯示，過去10年來全球臭氧的濃度降低了幾個百分點。

2、back up
支持，證實（某種說法）
Radio signals received from the galaxy's centre back up the black hole theory.
從該星系中心收到的無線電信號證實了黑洞理論。
Her views are backed up by a 1989 Home Office report on crime.
1989年內政部的一份犯罪報告印證了她的觀點。
備份（文件）
Make a point of backing up your files at regular intervals.
一定要定期備份文件。
I get so annoyed when I lose work because I've forgotten to back it up.
當我因為忘了備份把完成的工作弄丟時，真是懊惱極了。
將…付諸實施
The Secretary General says the declaration must now be backed up by concrete and effective actions.
秘書長說現在必須將宣言付諸具體有效的行動。
It is time the Government backed up its advert campaigns with tougher measures.
是政府采取更嚴厲的措施來兌現其宣傳承諾的時候了。