为效力英语的常用翻译是"to serve with effectiveness"。这个词组来源于英文动词"to serve"，意思是"服务，担任"，后面加上副词"effectively"，意思是"有效地"。因此，"to serve with effectiveness"就是"有效地服务"的意思。

下面是一些例句：

I want to serve with effectiveness in this position. 我希望在这个职位上有效地服务。

The teacher serves with effectiveness by using engaging teaching methods. 老师采用讲义生动的教学方法，有效地服务。

The organization aims to serve with effectiveness by providing high-quality services to the community. 该组织的目标是通过向社区提供高质量的服务，有效地服务。