quiet adj.安静的
quite adv.非常，很
quit v. 放弃

dairy 牛奶的，奶制的
diary 日记

angle：角度，观点
angel：天使

aboard 上飞机，上船
abroad 在国外
He was already aboard the plane. 他已经登上飞机了。
She worked abroad for a year. 她在国外工作了一年。

principal/principle
principal：n. 校长 adj. 主要的，最重要的
principle: n. 原则，准则，原理，定律
He's got no principles at all. 他一点原则都没有！
The principal has no principles. 这个校长没有原则！

stuff
used when you are talking about things such as substances, materials, or groups of objects when you do not know what they are called, or it is not important to say exactly what they are
可以形容单个物体，What's this stuff？
可以作为一个统称，比如，看看你桌上这些东西，Look at all the these stuff on your desk! 不讲stuffs。

staff
all the workers employed in an organization 全体员工全体职员，单形复义
The staff were very good. 职员们都很棒。

economic：economy的形容词，和经济，和财政有关的
economical：经济实惠的，节约型的
social, economic and political issues 社会的，经济的，政治的问题
an economical car 经济型汽车，节油型汽车
It's more economical to use gas than coal. 用天然气比烧煤更便宜。