1.rating n.等级：定额(a classification according to grade)
例：Ratings of productivity correlated highly with ratings of both accuracy and attendance. //Managers responded that productivity was the critical factor in assigning ratings.

2.ratio n．比例(proportion)

词根记忆：rat(计算)+io——和计算有关的——比例
例：Statistics show that the ratio of women's earnings with that of men have been roughly static since 1960.

3.ration n．定量配给（食物等）(fixed quantity, esp. an official allowance of food, etc. in times of shortage)
词根记忆：rat(计算)+ion——计算着给——配给
例：a rationing mechanism配给机制

4.rational a．合理的，理性的(having reason or understanding);n．有理数(an integer or a fraction)
词根记忆：ration(理性，定量)+al——理性的，合理的
例：The majority of successful senior managers do not closely follow the classical rational model of first clarifying goals.
派生词：rationally( ad.理性地)
同根词：rationalistic(a．理性主义的；纯理论的)

5.rationale n．根本性的依据（an underlying reason, basis）
词根记忆：rat(计算)+ion+ale——通过精密计算——根本性的依据
例：My professor disagreed with the rationale of my argument.

6.reactor n．起反应的人(one that reacts)；【原】反应堆(a device for the controlled release of nuclear energy)
词根记忆：react(反应)+or——发生反应的东西——反应堆
例：nuclear reactor核反应堆

7.readily ad.乐意地(willingly)；容易地(easily)
例：l Women accepted the more unattractive new industrial tasks more readily than did men.//Such foods are more readily available in China than in the U.S

8.realm n．领域(domain)；国度(kingdom)
联想记忆：real(真正的)+m——真正的好东西（如音乐，艺术）无国界——领域；国度
例：the realm of science科学领域

9.rear v.抚养(to bring up)；a．后面的(being at the back)
例：The identical twins were reared apart from each other.//rear wheel后轮