题目

-Look at the man in blue!Do you know    ？ -Oh，he is a policeman． A．what does he do   B．what he does C．how he does 答案：B在△ABC中，内角A，B，C所对的边长分别为a，b，c．asinBcosC+csinBcosA=12b且a＞b，则∠B=30°30°．