efficiency n．效率，功效
例句：Such action can only be justified on the grounds of greater efficiency.
只有以提高功效為依據可以證明采取這種措施是正確的。

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.
最近信息系統已稍加改動以提高效率。

proficiency n．精通，熟練程度
例句：Only through constant practice, can you improve your language proficiency quickly.
只有不斷練習，才能迅速提高語言的熟練程度。

deficiency n．缺乏，不足
例句：The deficiency of this plan is very clear, so it can't possibly succeed.
這項計劃的缺陷是很明顯的，所以它不可能成功。

deficit n．赤字,不足額
例句：The current trade deficit indicates a serious imbalance between the import and export trade of the small country.
當前的貿易赤字表明那個小國的進出口貿易嚴重失調。