efficiency n．效率，功效
例句：Such action can only be justified on the grounds of greater efficiency.
只有以提高功效为依据可以证明采取这种措施是正确的。

efficient adj. 生效的，有效率的，能干的
例句：The information system has recently been modified to make it more efficient.
最近信息系统已稍加改动以提高效率。

proficiency n．精通，熟练程度
例句：Only through constant practice, can you improve your language proficiency quickly.
只有不断练习，才能迅速提高语言的熟练程度。

deficiency n．缺乏，不足
例句：The deficiency of this plan is very clear, so it can't possibly succeed.
这项计划的缺陷是很明显的，所以它不可能成功。

deficit n．赤字,不足额
例句：The current trade deficit indicates a serious imbalance between the import and export trade of the small country.
当前的贸易赤字表明那个小国的进出口贸易严重失调。