By whom is the baby looked after?特殊疑问句,不是以特殊疑问词开头的吗?为什么这句话会以一个介词开头（我知道这句话是被动语态）?这是什么语法?

通常by不移到句首也可以,比如：The toy is made by a little girl. --> Whom is the toy made by?但是 原句中动词短语 looked after 是以介词 after 结尾,如果by 不提到句首,读起来不顺.同样的道理,The old man is t...