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时间:2018-10-27
《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,更多相关内容在教育资源-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,andtheinexperiencedgardenercanbeencouragedbythethoughtthatmoredamageresultsfromdoingitunnecessarilythanfro
2、mleavingthetreetogrowinitsownway. First,pruningmaybedonetomakesurethattreeshaveadesiredshapeorsize.Theobjectmaybetogetatreeoftherightheight,andatthesametimetohelpthegrowthofsmallsidebrancheswhichwillthickenitsappearanceorgiveitaspecialshape.Secondly,pruningmaybedonetomakethetreehealthier.Youmayc
3、utdiseaedordeadwood,orbranchesthatarerubbingagainsteachotherandthuscausewounds.Thehealthofatreemaybeencouragedbyremovingbranchesthatareblockingupthecentreandsopreventingthefreemovementofair. Oneresultofpruningisthatanopenwoundisleftonthetreeandthisprovidesaneasyentryfordisease,butitisawoundthatw
4、illheal.Oftenthereisaracebetweenthehealingandthedeseaseastowhetherthetreewillliveordie,sothatthereisaperiodwhenthetreeisatrisk.Itshouldbetheaimofeverygardenertoreducewhichhasbeenprunedsmoothandclean,forhealingwillbesloweddownbyroughness.Youshouldallowthecutsurfacetodryforafewhursandthenpaintitwit
5、honeofthesubstancesavailablefromgardenshopsproducedespeciallyforthispurpose.Pruningisusuallywithoutinterferencefromtheleavesandalsoitisveryunlikelythatthecutsyumakewillbleed.Ifthisdoeshappen,itis,ofcourse,impossibletopaintthemproperly. 1.Pruningshouldbedoneto______. a.makethetreegrowtaller b.i
6、mprovetheshapeofthetree c.getridofthesmallbranches d.makethesmallbranchesthicker 2.Treesbecomeunhealthyifthegardener______. a.allowstoomanybranchestogrowinthemiddle b.doesnotprotectthemfromwind c.forcesthemtogrowtooquickly d.damagessomeofthesmallsidebranches 3.Whyisaspecialsubstancepainte
7、donthetree? a.Tomakeawoundsmooth b.Topreventdiseaseenteringawound c.Tocoveraroughsurface d.Tohelpawoundtodry 4.Agoodgardenerprunesatree______. a.atintervalsthroughouttheyear b.asquicklyaspossible c.occasionally
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