cent/center/central/concentrate/focus/century/centigrade/centimeter/percent/percentage
记忆：
1. 词根cent 含义为一百或百分之一。cent n. 百分之一美元，美分
2. century n. 百年，世纪 Over centuries the customs here have changed a lot. 几百年来这儿的风俗发生了很大的变化。
3. grade 等级， centigrade （水的冰点到沸点间的温度分成一百分而得到的）摄氏度 The normal temperature should be 37°C. 正常的体温应是37°C。
4. meter音“米”，centimeter百分之一米，厘米
5. per-, 每；percent 每百中的， 百分之 Twenty percent of the population work on the farm.百分之二十的人在农场工作。
6. 加后缀-age, percentage n. 百分率 What’s the percentage of success?成功率有多少？
7. center n. 中间 With more countries joining the EU, the geological center of the EU has moved to a small German town. 随着更多的国家加入欧盟，一个德国小镇就成了欧盟的地理中心。
8. central adj. 中间的， 中央的 Is it a good thing to live in the central area? 生活在中心地带是不是一件好事呢？
9. 加前缀con-, 动词后缀-ate, concentrate v. 以为中心， 集中 While in class we must concentrate on what the teacher says.课堂上我们应专心听讲。
10. focus n. (兴趣活动等的)中心, 焦点, 焦距 vi. 聚焦, 注视 These days almost all the media focus on the Iraqi War.这些日子几乎所有的媒体都聚焦在伊拉克战争上。
另类阅读：
Over centuries people concentrate in the central areas of the city. The areas are overcrowded. More than 30 percent of people live in the room measured not by the square meter, but by the square centimeter. When summer comes, it may be as hot as 40° of centigrade.