Hokkien dialects are typically written using Chinese characters (漢字, Hàn-jī). However, the written script was and remains adapted to the literary form, which is based on classical Chinese, not the vernacular and spoken form. Furthermore, the character inventory used for Mandarin (standard written Chinese) does not correspond to Hokkien words, and there are a large number of informal characters (替字, thè-jī or thòe-jī; 'substitute characters') which are unique to Hokkien (as is the case with Cantonese). For instance, about 20 to 25% of Taiwanese morphemes lack an appropriate or standard Chinese character.

Answer this question, if possible (if impossible, reply "unanswerable"): What is used for Mandarin but doesn't correspond to Taiwanese words?
unanswerable