【英语时差8，16】造桥

 Suspension bridges such as the Golden Gate Bridge and the Brooklyn Bridge are some of the most amazing structures on earth. These aesthetic¹ and technological² wonders span rivers, and other obstacles with enough strength to support endless streams of cars and trucks. How do they do it?   All bridges routinely experience compression and tension. The vehicles that press down on a bridge's roadway compress the top half of the road, causing it to shorten like a compressed spring. The bottom half of the road experiences tension, meaning that it elongates³ like a spring pulled apart.

Suspension bridges are designed to absorb these forces in two ways: dissipation and transference. When a bridge dissipates force it spreads it out over a wider area. Transference involves moving force from a weak area to a stronger area.

Chances are you've seen a suspension bridge and maybe even crossed one. They consist of at least two large towers anchored to the ground, a roadway, and a web of steel cables strung between the towers and from each tower to the anchorages at either end. What's amazing is that the roadway is literally⁴ suspended in the air by the cables. It just hangs there as you and thousands of others drive across.

As the roadway hangs from the towers and vehicles move across its surface, the cables transfer the compression forces directly to the two towers, which in turn transfer the brunt of the pressure down into the ground. The cables also absorb much of the tension forces as they stretch under the weight of the roadway and traveling vehicles. Finally, the anchorages absorb some of the force as well.   

1 aesthetic   

adj.美学的，审美的，有美感

参考例句：

• My aesthetic standards are quite different from his.我的审美标准与他的大不相同。
• The professor advanced a new aesthetic theory.那位教授提出了新的美学理论。

2 technological   

adj.技术的；工艺的

参考例句：

• A successful company must keep up with the pace of technological change.一家成功的公司必须得跟上技术变革的步伐。
• Today,the pace of life is increasing with technological advancements.当今， 随着科技进步，生活节奏不断增快。

3 elongates   

v.延长，加长( elongate的第三人称单数 )

参考例句：

• Acropetal differentiation of the cambium layer continues as the primary root elongates. 形成层的向顶分化像初生根伸长一样在继续进行。 来自辞典例句
• At the onset of germination, the hypocotyl elongates rapidly by cell enlargement. 萌发开始时，下胚轴依靠细胞增大而迅速伸长。 来自辞典例句

4 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。