o pay, I'll sell it to you." 。After some haggling, they finally bought the cart for nineteen guan. Ye Da's mother drove the cart herself, while Ye Hou and his two children sat in the middle of the lug...In May of 884 AD, on the official road fifty li southwest of Bianzhou (modern-day Kaifeng) his pencil swinging back and forth: "Theoretically speaking, space and time are two dimensions, and they cannot be converted into each other. It's like we can't say that one hour equals 5 kilometers...