after he finished his work,______ he wanted to do next was to go home 为什么填what

问题描述:

after he finished his work,______ he wanted to do next was to go home 为什么填what
后面的从句为什么缺少成分,缺什么.

what 引导的 是 主语从句.
主语从句为:what he wanted to do.
what做 do 的宾语.
因为do 为及物动词,必须要有宾语,所以 填what.