Building a Bridge

Building a Bridge. Written by Ned Jensen. Illustrated by Fred Volk.

《建一座桥》 撰文：内德·詹森 绘图：弗雷德·沃尔克

Bridges go over rivers and lakes. They go over bays and swamps. They go over highways and railroads. Some even float.

桥梁横跨河流与湖泊。 它们横跨海湾与沼泽。 它们横跨公路与铁路。 有些桥甚至是浮在水面上的。

Bridges are long and short. They can be high above the water. They can be near the water. They can carry cars, trucks, trains, and buses. Some carry people. Some carry water or oil.

桥有长有短。 它们可以高高耸在水面上方。 也可以修得离水面很近。 它们可以通行小汽车、卡车、火车和公交车。 有些桥供行人通行。 有些桥用来输送水或者石油。

The first bridges were made out of wood, rope, or stone. Today, most bridges are made of steel and concrete.

最早的桥是用木头、绳索或者石头建造的。 如今，大多数桥是用钢材和混凝土建造的。

The first bridges were simple. Some were just logs placed across a stream. Some were ropes stretched across a river.

最早的桥结构很简单。 有些不过是横放在小溪上的原木。 有些是绷在河两岸的绳索。

Later, stones were used to build stronger and longer bridges. In time, people were building bridges like the ones we see today. These are made of concrete and steel. They go across longer distances.

后来，人们用石头建造更坚固、更长的桥。 渐渐地，人们造出了和我们现在看到的一样的桥。 这些桥用混凝土和钢材建成，可以横跨更长的距离。