thinking（n.） 英 [´θɪŋkɪŋ] 美 [´θɪŋkɪŋ] "act of conceiving in the mind, the mental action of one who thinks, exercise of cogitation," mid-14c., verbal noun from think (v.). The figurative thinking cap is attested from 1839.该词起源时间：14世纪中期
