【正确答案】I had not expected that this shameless woman should flirt with her best friend's husband.

【答案解析】shameful通常指某事物是“可耻的，丢脸的”，而shameless表示having or showing no feelingof shame，它一般用来指人“不知羞耻的，不要脸的”或“伤风败俗的”。