单项选择题
A.would do;helpB.could have done;to helpC.would have done;helpingD.could do;helped
A.产婆术B.问答法C.讲授法D.发现法
A.负有保密义务B.不负有保密义务C.在一定情况下负有保密义务D.在一定情况下不负有保密义务