【正确答案】赞同实施安乐死的人这样认为：医生的职责之一就是避免痛苦，有时候他们唯一能做的就是对病人实施安乐死。

【答案解析】[翻译要点] 本句事实上由三个分句构成：1．Their argument for killing goes like this；2．one of a doctor’s duty is to prevent suffering；3．some times that is all there is left for him to do，and killing is the only way to do it.可采取分译法分开叙述。难点有：prevent suffering译为“避免痛苦”，all there is left for him to do，is the only way to do it.可译为唯一能做的。