whatever is worth doing at all is worth doing （it） well.为什么 括号里的it 必须省略

题目

whatever is worth doing at all is worth doing （it） well.为什么 括号里的it 必须省略

答案

be worth doing 啊
this task -------- is worth dong well.加个名词或者指代不明的it才奇怪吧~