阅读理解。 |
Spiderwebsareoneofthemostfascinatingexamplesofanimalarchitecture.Themost
beautifulandstructurallyorderedaretheroundwebs.Themainfunctionofthewebistostop andholdflyinginsects,longenoughforthespidertocatchthem.Inordertodoso,thethreads ofthewebhavetostandtheforcesfromlargeandheavyinsectsaswellasenvironmentalforces fromwindandrainforatleastadayinmostcases. Theroundwebisfoundtohavetwomaincharacteristics.Thefirstisitsgeometry,which consistsofanouterframeandacentralpartfromwhichthreadsradiateoutward.Enclosedin theframearecapturespiralswindingroundandroundfromthewebcenterouttotheframe. Thewholewebisintensionandheldinplacebyanchorthreads,whichconnecttheframetothe surroundingplantsorobjects.Thesecondandperhapsmostimportantcharacteristicisthe materialwithwhichitisbuilt.Spidersilkisakindofnaturalmaterialthatgivesthislightweight fiberastrengthcomparabletothatofsteel,whileatthesametimemakingitveryelastic(有弹性的). Twotypesofsilkthreadsareusedintheweb.Oneishighlyelasticandcanstretchtoalmosttwice itsoriginallengthbeforebreakingand,formosttypesofspiders,iscoveredinglue.Thistypeis usedinthecapturespiralforcatchingandholdinginsects.Theotherisstifferandstronger,andis usedfortheradius,framesandanchorthreads,whichallowsthewebtostandforcesandtokeep itsstructuralstrengththroughawiderangeofenvironmentalconditions. |
l.Whatdoestheword"so"inthefirstparagraphreferto? |
A.Tocatchandkeepsmallcreatures.
B.Tofindagoodmaterialfortheweb. C.Tomakethewebsbeautifulandwellordered. D.Tomakethethreadslongenough. |
2.Whichofthefollowingisusedforcatchingandholdinginsects? |
A.Thecenteroftheweb.
B.Thecapturespirals. C.Theanchorthreads. D.Theradius. |
3.Whichofthefollowingcorrectlygivesthenamesofthenumberedthreadsinthepicture? |
A.①capturespiral②radius
B. 毛涛回答:
1-5:ABDDC
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