i don't know when to do it.为啥要加it?而 when to go后则不需加别的啥呢?

i don't know when to do it.为啥要加it?而 when to go后则不需加别的啥呢?
i don't know when to do it.为啥要加it?而 when to go后则不需加别的啥呢?

i don't know when to do it.为啥要加it?而 when to go后则不需加别的啥呢?
do 是及物动词 必须加宾语.而 when 属于疑问副词 不能做宾语.如果是疑问代词就不用加it 如：I don't know what to do.
而go 是不及物动词 不需要也不能直接 接宾语