pro·fi·cien·cy
noun/prəˈfɪʃnsi/
/prəˈfɪʃnsi/
[uncountable]- the ability to do something well because of training and practice
熟练：由于训练和实践而擅长做某事的能力 - to develop proficiency
提高熟练程度 - a certificate of language proficiency
语言水平证书 - proficiency in something/in doing something a high level of oral proficiency in English
一口流利的英语
- to develop proficiency