From the contents of his shopping basket, I deduced that he was single.

deduced 是动词 deduce 的过去式。deduce 由前缀 de-（表示"向下、彻底"）和词根 duce（来自拉丁语 ducere，意为"引导"）组成，字面意思是"彻底引导出结论"，即"通过逻辑推理得出结论"的意思。