国家地理-2008-07-05 Surviving the Tornado 龙卷风来袭大难不死

A tornado¹ rips across the Missouri Plains. Winds over 150 miles per hour shred² everything in the twister's path. When it smashes a trailer home, one man is sucked into the heart of the storm, spun³ and shaken horrifically. His limp body drops out of the sky a quarter of a mile away.

 "It was crazy. I knew that I wasn't where I supposed to be, and it took me a minute to realize, you know, what was happening."

 Matt hasn't broken a single bone. How could that be? Scientists estimate Matt hit the ground traveling at least 30 miles an hour. Yet his bones protected his internal organs from being smashed.

 "Lock the door."

 "Got it."

 Our skeleton is made up of 206 bones, from the largest in our legs and arms to the tiny bones in our toes and fingers. They give us the tough flexible frame that lets us push and pull on our will.

 Bone is incredibly strong.

 Pound for pound, bone is stronger than concrete. It has a strength-to-weight ratio found in no other natural material on earth.

 The secret of bone's strength and lightness lies inside. It is a matrix of hollow cells; its walls are as thin as paper.

 Bone gets its rigidity⁴ from calcium⁵ and phosphorus, materials found in seashells and teeth. But astonishingly, almost half of our bone mass is soft and alive, allowing our bones to bend.

 Every seven years, a healthy human body completely replaces every single bone cell. This renewal⁶ keeps our bones incredibly strong and uniquely adaptable⁷.

 Notes:

strength/weight ratio: The relationship between the structural⁸ strength of a material and its weight.
bone mass: The amount of mineral in a bone. Although this is different from bone density⁹, the terms are often used interchangeably.

1 tornado   

n.飓风，龙卷风

参考例句：

• A tornado whirled into the town last week.龙卷风上周袭击了这座城市。
• The approaching tornado struck awe in our hearts.正在逼近的龙卷风使我们惊恐万分。

2 shred   

v.撕成碎片，变成碎片；n.碎布条，细片，些少

参考例句：

• There is not a shred of truth in what he says.他说的全是骗人的鬼话。
• The food processor can shred all kinds of vegetables.这架食品加工机可将各种蔬菜切丝切条。

3 spun   

v.纺，杜撰，急转身

参考例句：

• His grandmother spun him a yarn at the fire.他奶奶在火炉边给他讲故事。
• Her skilful fingers spun the wool out to a fine thread.她那灵巧的手指把羊毛纺成了细毛线。

4 rigidity   

adj.钢性，坚硬

参考例句：

• The rigidity of the metal caused it to crack.这金属因刚度强而产生裂纹。
• He deplored the rigidity of her views.他痛感她的观点僵化。

5 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

6 renewal   

adj.(契约)延期，续订，更新，复活，重来

参考例句：

• Her contract is coming up for renewal in the autumn.她的合同秋天就应该续签了。
• Easter eggs symbolize the renewal of life.复活蛋象征新生。

7 adaptable   

adj.能适应的，适应性强的，可改编的

参考例句：

• He is an adaptable man and will soon learn the new work.他是个适应性很强的人，很快就将学会这种工作。
• The soil is adaptable to the growth of peanuts.这土壤适宜于花生的生长。

8 structural   

adj.构造的，组织的，建筑（用）的

参考例句：

• The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
• The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。

9 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。