— John, my computer doesn't work.

— Why not ask Mr Liu _____ it? [ ]

A. to buy

B. not to buy

C. to check

D. not to check

从全科医疗的服务模式来看，全科医生在整个服务过程中始终贯彻哪一项原则

A．预防为主

B．实事求是

C．可持续发展

D．以区域卫生规划为指导

E．分类指导