Concentration on something involves giving all your attention to it.
例句
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。
N-VAR
集中;匯集
A concentration of something is a large amount of it or large numbers of it in a small area.
例句
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。
N-VAR
濃度
The concentration of a substance is the proportion of essential ingredients or substances in it.
例句
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。