For example, in Roman times, engineers discovered that if the upstream supports of a bridge were shaped to offer little resistance to the current of a stream or river, they would last longer.
例如，在罗马时代，工程师们发现如果桥的上游的桥墩建成对目前河流水阻力小的形状，桥墩的寿命会更长。
2
366 - the Alamanni cross the frozen Rhine River in large Numbers, invading the Roman Empire.
366年的今天，阿拉曼人大量越过冰封的莱茵河，入侵罗马帝国。
3
A river of Czechoslovakia and Germany flowing about 1,167 km (725 mi) to the North Sea. It has been a major waterway since Roman times.