We work together to achieve our common purpose: _______ world that is safer, cleaner and healthier than_______ one we are living in.

A．the;/

B．a; /

C．the; the

D．a; the

国内游客丢失身份证，应由___________核实后开具证明，失主持证明到___________报失，经核实后开具身份证明，机场安检人员核准放行。