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SSS 2009-06-11

时间:2010-05-18 02:42来源:互联网 提供网友:mark@li   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American's 60-second Science. I'm Karen Hopkin. This will just take a minute.

 What do a hummingbird1, a moth2, and a maple3 tree have in common? They all use a similar trick to fly. Okay, okay, a maple tree doesn’t fly. But its seeds kind of do. Maples4 make those little whirlybird seeds you see spiraling down in droves each spring. Their papery little wings keep them aloft so they can find a good place to germinate5 and make a new maple. But how they manage to fall so slowly has been a bit of a mystery—until now.

Scientists filmed maple seeds as they wafted6 through a smoke-filled wind tunnel. And they found that a spiral of air develops on top of each falling seed’s wing. That vortex generates lift, and acts like a miniature tornado7 that sucks the seed up. The study appears in the June 12th issue of the journal Science.

The same type of vortex also helps bats, hummingbirds8 and insects soar. So it seems that plants and animals have both stumbled on the same aerodynamic approach to battling gravity. Which explains why the acorn9 might not fall far from the tree, but maple seeds can really go the distance.

 

Thanks for the minute for Scientific American's 60-second Science. I'm Karen Hopkin.
 


点击收听单词发音收听单词发音  

1 hummingbird BcjxW     
n.蜂鸟
参考例句:
  • The hummingbird perches on a twig of the hawthorn.小蜂鸟栖在山楂树枝上。
  • The hummingbird is the only bird that can fly backward.蜂鸟是唯一能倒退向后飞的鸟。
2 moth a10y1     
n.蛾,蛀虫
参考例句:
  • A moth was fluttering round the lamp.有一只蛾子扑打着翅膀绕着灯飞。
  • The sweater is moth-eaten.毛衣让蛀虫咬坏了。
3 maple BBpxj     
n.槭树,枫树,槭木
参考例句:
  • Maple sugar is made from the sap of maple trees.枫糖是由枫树的树液制成的。
  • The maple leaves are tinge with autumn red.枫叶染上了秋天的红色。
4 maples 309f7112d863cd40b5d12477d036621a     
槭树,枫树( maple的名词复数 ); 槭木
参考例句:
  • There are many maples in the park. 公园里有好多枫树。
  • The wind of the autumn colour the maples carmine . 秋风给枫林涂抹胭红。
5 germinate hgSx1     
v.发芽;发生;发展
参考例句:
  • Seeds will not germinate without water.没有水,种子是不会发芽的。
  • Can thin and hollow seeds germinate?瘦瘪的种子能够发芽吗?
6 wafted 67ba6873c287bf9bad4179385ab4d457     
v.吹送,飘送,(使)浮动( waft的过去式和过去分词 )
参考例句:
  • The sound of their voices wafted across the lake. 他们的声音飘过湖面传到了另一边。
  • A delicious smell of freshly baked bread wafted across the garden. 花园中飘过一股刚出炉面包的香味。 来自《简明英汉词典》
7 tornado inowl     
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。
8 hummingbirds 86894f7ac4de81bc2d81331e9759a43b     
n.蜂鸟( hummingbird的名词复数 )
参考例句:
  • Hummingbirds have discovered that nectar and pollen are very nutritious. 蜂鸟发现花蜜和花粉是很有营养的。
  • Why do hummingbirds and gorillas both have backbones? 为什么蜂鸟和大猩猩都有脊骨?
9 acorn JoJye     
n.橡实,橡子
参考例句:
  • The oak is implicit in the acorn.橡树孕育于橡子之中。
  • The tree grew from a small acorn.橡树从一粒小橡子生长而来。
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