词汇讲解：

1.concentration 集中, 专心, 浓度
如：
The tennis players need total concentration during play.
网球运动员在比赛中需要全神贯注.

Stress and tiredness often result in a lack of concentration.
紧张和疲劳常使人精神不集中。

2.fluctuate vt. 使动摇
如：
To fluctuate or waver in making choices; vacillate.
犹豫选择时来回摆动；摆动

3.demonstrate 示范, 演示, 证明

如： She demonstrated that 2 and 2 are four.
她证明2加2等于四。

Please demonstrate how the machine works.
请示范机器的使用方法。

4.scarcely 几乎不, 简直没有, 勉强
如：
He spoke scarcely a word of English.
他几乎连一个英文单词都不会说。

Scarcely had he arrived when he had to leave again.
他刚刚到达就不得不又离开。

5.distractor 分散注意力的东西

(可可英语版权所有,未经允许请勿转载)