Did you ever say goodbye to someone knowing it would be forever?这句话knowing非谓语做主动的定语从句没有加逗号 是否应该将从句的主语认定为someone(即someone knows it would be forever)?还是与在knowing前加逗号一样将从句主语认定为you?
根据grammarly, participle phrase/clause修饰的是挨着它的名词, 和有没有逗号无关. 修饰宾语的时候一律不加逗号, 修饰主语的时候, 如果是限制性的(也就是说必不可少的)就不加逗号, 如果是非限制性的就要加逗号. 原句可以改成: Did you ever say goodbye to someone while you knew it would be forever?