When I visited Wisconsin Farm Technology Days last year, John Deere was letting visitors test its 8530 tractor, an electromechanical marvel so sophisticated that I had no idea how to operate it.

• 我去年参加威斯康辛农场科技节时，宝鹿公司正好让参观民众试驾型号8530的曳引机，不过这台令人惊奇的电子机械车太过复杂，我根本不知道如何操作。