单项选择题
A．was accepted by everybody B．caused heated arguments C．was probably accepted by his court D．Was not believed by anyone except himself
A．they are innocuous agencies B．they are the causative agents of most human cancer C．they seem to be infections to many people D．they are generally thought to be relevant to most cancer in man
A．Athletic and recreational. B．Food and transportation. C．Bookstore and post office. D．Medical and audio-visual (视听的).