供参考 这里何以用 as,which 或 that 不可以用 what 用which或that 便构成代名词的从句 即 which/that are considered helpful to others 而 which 及 that 是指 criticisms 如果用 what 就会变成 名词短句 而在这句子中便要做宾语 若要符合语法 原句将会改为 He never hesitates to say something(他从不犹豫说一些话儿) 再将 something用 what are considered helpful to others来取代 亦即变成了 He never hesitates to say what are considered helpful to others. 留意的是 这里要用 say 来取代 make 因为取消了 criticisms之后 make的意思就不明确了 这也就是说 不能够改为 He never hesitates to make what are considered helpful to others. 至於为何可以用as 原因这是as的一种惯用法 可以这样的说 原句是 as they are considered helpful to others. 但很多时 they这主语会被省略 (条件是其所代表的名词在同一句子内的前文出现) 所以便有 as are considered helpful to others 值得留意的是 更常见的是 as is 即是 as it is