The time he has devoted in the past ten years _____the disabled is now considered ____of great value. [ ]

A. to help; being

B. help; to be

C. to helping; to be

D. helping; being

服务圈是一个（）的工具。

A、分解服务过程

B、找出每个细节的关键因素

C、把关键因素转化为服务标准

D、根据客户需求对标准重新评估和修改