The artist's work was full of creativity, even though he was untaught in formal techniques.

### 解释 untaught 是由前缀 un-（表示"没有、未"）和动词 teach（"教、训练"）的过去分词 taught 组合而成的形容词，字面意思是"未被教导的"，引申为"未经正规训练的"。