— Look, that's Tom-the lost boy!

— It's really     great comfort to see him safe again. He is sure to bring        comfort to his worried mother.[ ]

A. a; a            

B. the; the          

C. a; /            

D. the; /

若发现已生效的行政执法行为违法或不当，则( )。

A．原行政机关无权废止

B．原行政机关或上级行政机关有权撤销

C．只有权力机关有权撤销

D．相对一方当事人有权变更