定语从句do you know the reason why he didn't come?为什么可以用why?从句后he是主语,didn't come是谓语,不是缺宾语吗?那怎么还可以用why

定语从句do you know the reason why he didn't come?为什么可以用why?从句后he是主语,didn't come是谓语,不是缺宾语吗?那怎么还可以用why
定语从句do you know the reason why he didn't come?为什么可以用why?从句后he是主语,didn't come是谓
语,不是缺宾语吗?那怎么还可以用why

定语从句do you know the reason why he didn't come?为什么可以用why?从句后he是主语,didn't come是谓语,不是缺宾语吗?那怎么还可以用why
英语中规定：定语从句中的先行词reason 一律用 why做其引导词.
come 是不及物动词,后面不需要加宾语

不缺，前面一句主谓宾都有，why 是指代的reason，后面的he didn't come是why的内容。可以说reason 和why 是一个东东。而后面的是对why 的进一步解释。
整句意思是，你知道他没有来的原因吗？