A qualified doctor has to constantly update his knowledge in order to maintain his profess

问题补充：

A qualified doctor has to constantly update his knowledge in order to maintain his professional .

A. conscience

B. competence

C. conservation

D. convenience

答案：

A. conscience

(答案→)B. competence

C. conservation

D. convenience

解析：A. conscience意识，B. competence能力，C. conservation保护，D. convenience便利，句意：一个合格的医生不得不不断的更新他的知识为了保持他的专业技能。选B。