单项选择题
A．athlete: compete B．salary: tax C．stake: gamble D．production: invent E．role: act
A．visible: sight B．unbreakable: glass C．porous: liquid D．slippery: glue E．reflective: hamper
A．savant: doctrine B．criminal: arson C．coward: cravenness D．schoolmate: sociability E．expert: amateurism