They had made a mess of the house.
这句话改被动:
动宾做主语:A mess had been made of the house.
介宾做主语:The house had been made a mess of.
为啥这两句中都没有原句中的主语They 啊?不能在后面加上by them 吗?是有动宾和介宾都这样吗?我做了几个take care of, pay attention to 改被动都不加原句中的主语,这到底是怎么回事啊?求大神解惑.
一般情况下,如果动作执行者不可知或者不易说明,或者上下文清楚等,通常省略 by 短语。在网友的句子后面也可以加上by them。