mercy killing安乐死
show mercy of对...表示宽容
mercy
n.
仁慈, 宽恕, 怜悯
a heart full of mercy.
充满包容的心
It was a mercy that no one was hurt.
没有人受伤真是幸运
have mercy on sb.=show mercy to sb.对某人怜
at the mercy of任由……摆布
mercy :n.仁慈，慈悲；宽大，宽恕的意思.
be at the ~ of 听任．．．的摆步；have /take ~ on/upon 怜悯