最早的桥首先要说清楚:什么是桥?如果说,能使人过河,从此岸到彼岸的东西就是桥,那么,船也是桥了;能使人越岭,从这山到对山的东西就是桥,那么,直升机也是桥了。船和飞机当然都不是桥,因为桥是固定的,而人在桥上是要走动的。可是,拦河筑坝,坝是固定的,而人又能 The earliest bridge must first make it clear: what is a bridge? If it can make people cross the river, from the shore to the other side is the bridge, then the ship is also a bridge; can make people more, from the mountain to the mountain What is the bridge, then, the helicopter is also a bridge. Of course, neither the ship nor the plane is a bridge, because the bridge is fixed, and people are walking around the bridge. However, the dam building dam, the dam is fixed, and people can