忘恩负义（忘恩負義）　

◎ 忘恩负义 wàng’ēn-fùyì

[forgetful;turn on one‘s friend;kick away the ladder;be devoid of all gratitude] 忘却别人对自己的好处,做事有损于过去的恩义

如此忘恩负义,以致弄到牺牲盟国去订“密约”的地步