“Spider silk has been winning this competition for a long time,”Asa Barber,an engineer at the University of Portsmouth,England,who led the study said.“36.　” 

　　A limpet has about a hundred teeth,each about 1 millimeter(0.04 inches) long.37.　 To find out just how tough limpet teeth are,Barber’s team examined pieces of the limpets’ teeth to test their tensile strength—the resistance of a material to breaking when stretched.The scientists learned that the material that makes up limpet teeth can withstand a pulling force comparable to that of a rope lifting about 1,500 kilograms(3,300 pounds) of sugar. 

　　38.　 They contain fibers made from a combination of goethite and chitin.39.　 Chitin,on the other hand,is stretchy(有弹性的).Mix the two together,and you get a material that’s both hard and tough. 

　　In fact,limpet teeth are 10 percent stronger than spider silk.Scientists have had a hard time trying to artificially produce spiders’ sticky web material in a lab,but Barber believes it will be easier to recreate limpet teeth.40.　 “I think this is going to be a much greater opportunity to manufacture materials that have high strength,”he says. 

　　A.What makes limpet teeth so strong?

　　B.Though hard,goethite breaks easily.

　　C.A limpet has a tongue covered with tiny teeth.

　　D.It uses them to get its preferred meal off rocks.

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