As an Chinese saying goes that“Nothing can be accomplished without norms or standards”. Thus People always fol?low Cooperative Principle to produce successful conversations in daily life and the EFL teaching is of no exception. Teachers and students cooperate with each other in classroom while they sometimes flout the principle deliberately. Therefore, it is necessary to conduct research on interactions in classroom, especially question & answer behaviors to see how teachers and students observe the Cooperative Principle and analyze underlying causes of their intentional flouting .