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时间:2018-11-29
《大学英语四级阅读理解试题及答案(四)》由会员上传分享,免费在线阅读,更多相关内容在应用文档-天天文库。
1、大学英语四级阅读理解试题及答案(四)十六 Treesshouldonlybeprunedwhenthereisagoodandclearreasonfordoingsoand,fortunately,thenumberofsuchreasonsissmall.Pruninginvolvesthecuttingawayofobergrownandunwantedbranches,andtheinexperiencedgardenercanbeencouragedbythethoughtthatmoredamageresultsfromdo
2、ingitunnecessarilythanfromleavingthetreetogrowinitsownway. First,pruningmaybedonetomakesurethattreeshaveadesiredshapeorsize.Theobjectmaybetogetatreeoftherightheight,andatthesametimetohelpthegrowthofsmallsidebrancheswhichwillthickenitsappearanceorgiveitaspecialshape.Secon
3、dly,pruningmaybedonetomakethetreehealthier.Youmaycutdiseaedordeadwood,orbranchesthatarerubbingagainsteachotherandthuscausewounds.Thehealthofatreemaybeencouragedbyremovingbranchesthatareblockingupthecentreandsopreventingthefreemovementofair. Oneresultofpruningisthatanopen
4、woundisleftonthetreeandthisprovidesaneasyentryfordisease,butitisawoundthatwillheal.Oftenthereisaracebetweenthehealingandthedeseaseastowhetherthetreewillliveordie,sothatthereisaperiodwhenthetreeisatrisk.Itshouldbetheaimofeverygardenertoreducewhichhasbeenprunedsmoothandclea
5、n,forhealingwillbesloweddownbyroughness.Youshouldallowthecutsurfacetodryforafewhursandthenpaintitwithoneofthesubstancesavailablefromgardenshopsproducedespeciallyforthispurpose.Pruningisusuallywithoutinterferencefromtheleavesandalsoitisveryunlikelythatthecutsyumakewillblee
6、d.Ifthisdoeshappen,itis,ofcourse,impossibletopaintthemproperly. 1.Pruningshouldbedoneto______. a.makethetreegrowtaller b.improvetheshapeofthetree c.getridofthesmallbranches d.makethesmallbranchesthicker 2.Treesbecomeunhealthyifthegardener______. a.allowstoomanybran
7、chestogrowinthemiddle b.doesnotprotectthemfromwind c.forcesthemtogrowtooquickly d.damagessomeofthesmallsidebranches 3.Whyisaspecialsubstancepaintedonthetree? a.Tomakeawoundsmooth b.Topreventdiseaseenteringawound c.Tocoveraroughsurface d.Tohelpawoundtodry 4.Agoodg
8、ardenerprunesatree______. a.atintervalsthroughouttheyear b.asquicklyaspossible c.occasionally
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