Thewebsthatspiders(蜘蛛)buildtocatchinsectsseemweak.Howeverthestrengthofspiderthreadisgreaterthansteel.Webscanevenstanduptoverystrongstorms.

Ineachspiderwebsomethreadsaresticky(粘的)butsomearenot.Whenaspiderismovingonthewebitwillnotsteponthestickythreads.Afteratimethesilkwillloseitsstickinessandbecomeunabletocatchinsects.Thenspidersusuallyeattheirownweb.

Nowateamofscientistshasworkedoutwhythespiderwebissostrong.Itisnotjustthestrengthofthethreadbutthecleverdesignoftheweb.Thekeytoaweb’ssuccessisitsabilitytokeepitsshapeandstrengthevenaftersomeofthethreadsbreaksayscientistsattheMassachusettsInstituteofTechnology.Thescientistsfoundthethreaditselfhastheabilitytobecomesofterorharder.Soitcanholddifferenttypesofheavythings.

Intestsscientistsusedthreeotherstrongmaterials(材料)madeintothesamewebs.Thespiderthreadwassixtimesstrongerthananyothermaterial.Moresurprisinglywhenthescientiststookawayupto10percentofthethreadsfromdifferentplacesthewebdidn’tbecomeanyweaker.Actuallyitbecameupto10percentstronger.

Thespiderweb’scleverdesigngivesscientistsmanynewideas.Thefindingscouldhelpdesignsaferbuildingsandevenanewtypeofstrongmaterial.“It’sareallygoodchance”saidMarkusBuehleraprofessoratMIT.“Itmaygiveussomenewideasforengineering.”

1.Accordingtothepassagethespiderwebisstrongbecause.

a.thespider’sthreadissticky

b.thethreadhasalotofstrength

c.thewebhasacleverdesign

d.thewebcankeepthestrengthforever

A.abB.acC.bcD.bd

2.Inparagraph4thescientists’testsshowthat.

A.thespider’sthreadisstrongerthantheotherthreematerials

B.thespider’sthreadisthestrongestmaterialintheworld

C.thespider’sthreadcanbeassoftorhardasitneedstobe

D.takingawaysomespiderthreadmakesthewebweaker

3.Fromthelastparagraphwelearnthat.

A.peoplecanusespiderwebstobuildhouses

B.thefindingsgivepeoplenewideasforbuildings

C.therearemanyreasonsw