用That which 來代替what的用法非常少見，很詩意
That which you search for, is also seeking you.
That which is Below corresponds to that which is Above.
The thing that/which I would like you to work on ...(原始樣貌)
而The thing that/which 可以用What替代 (這題的答案)
也可以省略關代變成 The thing I would like you to work on...