the employees' working efficiency, the supervisor will allow them to have a coffee break.
A. Improving
B. To improve
C. Having improved
D. Improved
网友回答
A. Improving
(答案→)B. To improve
C. Having improved
D. Improved
解析：考察不定式做目的状语。意思说：为了改善员工的工作效率，老板允许他们有喝咖啡休息时间.to do 可以表示为了…. 实际上等同于in order to，so as to.