他的回答很零散，完全看不出逻辑。

His answers were disjointed and lacked any clear logic.

disjointed 是由前缀 dis-（表示"否定、分离"）和 joint（"连接、关节"）加上后缀 -ed 构成的形容词。joint 本意是"关节、连接处"，disjoint 表示"使脱节、使分离"，disjointed 形容事物"不连贯的、支离破碎的"。