“Whatever is worth doing at all is worth doing well”句首的不是主语从

我觉得这个句子中的at all 是无意义出现的 = =
whatever 就是无论什么. 无论是什么值得被做的事情都值得被做好.
你说的句子是当 that位于句首时作主语时不能省略的情况 而这时的that后面跟的那个句子是对句首的 that 起到补充说明的作用
That (we are invited to a concert this evening ) is good news to us. 比如这句 that 的出场起到了句中主语的作用
而whatever可以变形为 no matter what
(No matter) what is worth doing is worth doing well.
no matter 你可以放入句中 那么这个句子里就已经存在主语了 所以不用用到 that
That the things which are worth doing is worth doing well is true.