mono-wheel cart should be invented before 4wheel cart. it should

来源: 于 2009-07-03 15:13:54 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

mono-wheel cart should be invented before 4wheel cart. it should exist 2500 years ago. you can see the bronze 4wheel cart that was found in the Chinese First Empire's tomb.