efficiency的词性变形

efficiency n. 效率；效能；功效；提高功效的方法；功率

efficiency的副词是efficiently有效地；效率高地

例句：She deals with all the correspondence promptly and efficiently.

她迅速有效地处理全部来往信件。

Which fuel burns most efficiently?

哪种燃料燃烧效果最佳？