Wonder Webs
Spider webs are more than homes, and they are ingenious traps. And the worlds best web spinner may be the Goldern Orb Weaver spider. The female Orb Weaver spins a web of fibers thin enough to be invisible to insect prt, yet _____1____ enough to snare a flying bird without breaking.
The secret of the webs strength? A type of super-resilient ____2____ called dragline. When the female spider is ready to ____3_____ the webs spokes and frame, she uses her legs to draw the airy thread out through a hollow nozzle in her belly. Dragline is not sticky, so the spider can race back and forth along ____4___ to spin the webs trademark spiral.
Unlike some spiders that weave a new web every day, a Golden Orb Weaver _____5_____ her handiwork until it falls apart, sometimes not for two years1. The silky thread is five times stronger than steel by weight and absorbs the force of an impact three times better than Kevlar, a high-strength human-made ____6____ used in bullet-proof vests. And thanks to its high tensile strength, or the ability to resist breaking under the pulling force called tension, a single strand can stretch up to 40 percent longer than its original _____7____ and snap back as well as new. No human-made fiber even comes ____8____.
It is no ____9____ manufacturers are clamoring for spider silk. In the consumer pipeline: high-performance fabrics for athletes and stockings that never run2. Think parachute cords and suspension bridge cables. A steady _____10_____ of spider silk would be worth billions of dollarsbut how to produce it? Harvesting silk on spider farms does not ____11_____ because the territorial arthropods have a tendency to devour their neighbors.
Now, scientists at the biotechnology company Nexia are spinning artificial silk modeled after Goldern Orb dragline. The ____12____ step: extract silk-making genes from the spiders. Next, implant the genes into goat egg cells. The nanny goats that grow from the eggs secrete dragline silk proteins in their ______13____ . The young goats pass on the silk-making gene without____14____ help from us, says Nexia president Jeffrey Turner. Nexia is still perfecting the spinning process, but they hope artificial spider silk will soon be snagging customers ____15____ the real thing snags bugs.
1. A) tough B) soft C) large D) smooth
2. A) cloth B) silk C) nylon D) wool
3. A) repair B) pull C) move D) weave
4. A) him B) her C) it D) those
5. A) refixes B) reproduces C) remakes D) reuses
6. A) metal B) mass C) material D) model
7. A) bredth B) length C) height D) strength
8. A) close B) well C) open D) awake
9. A) hurry B) worry C) wonder D) use
10. A) shipment B) supply C) run D) exchange
11. A) run B) go C) deal D) work
12. A) previous B) foremost C) first D) front
13. A) milk B) meat C) lungs D) muscle
14. A) no B) any C) some D) many
15. A) as fast as B) as gently as C) as fully as D) as little as
参考答案:ABDCD CBACB DCABA
背1遍就想上考场四级单词74
大学英语四级词汇m
大学英语四级考试(CET4)历年真题听力2010年12月英语四级真题听力
大学英语四级词汇g
赵丽教你巧记英语单词LESSON 18
赵丽教你巧记英语单词LESSON 17
大学英语四级词汇d
赵丽教你巧记英语单词LESSON 51
大学英语四级词汇u
大学英语四级词汇q
CET4淘金式英语词汇(四级)第4课
大学英语四级词汇a
2008年6月四级预测卷听力(星火)第5课
赵丽教你巧记英语单词LESSON 3
大学英语四级词汇c
背1遍就想上考场四级单词26
赵丽教你巧记英语单词LESSON 40
赵丽教你巧记英语单词LESSON 39
星火英语2008年6月版听力强攻第1课
星火英语点评历年四级真题2006年12月四级真题
赵丽教你巧记英语单词LESSON 27
赵丽教你巧记英语单词LESSON 81
新四级听力听写练习第四单元lesson18
赵丽教你巧记英语单词LESSON 24
赵丽教你巧记英语单词LESSON 33
闭着眼睛飘单词四级notion- occupation
赵丽教你巧记英语单词LESSON 52
大学英语四级词汇b
2008年6月四级预测卷听力(星火)第2课
CET4淘金式英语词汇(四级)第1课
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |