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、challenge

挑戰;難題

I like a big challenge and they don't come much bigger than this.

我喜歡大的挑戰，而所有挑戰中再沒有比這更大的了。

The new government's first challenge is the economy.

新政府面臨的第一個難題是經濟問題。

(成功地)應對挑戰，迎接挑戰

The new Germany must rise to the challenge of its enhanced responsibilities.

一個嶄新的德國必須迎接挑戰，承擔更多的責任。

They rose to the challenge of entertaining 80 schoolchildren for an afternoon.

他們一個下午成功接待了80名學童。