距离2017年6月大学英语四级考试还有一个半月的时间，已经报名的同学备考一定要抓紧，不要临时抱佛脚。新东方网英语四级频道为大家整理了英语四级阅读理解每日一练，每天一道题考试不担心。
Treesshouldonlybeprunedwhenthereisagoodandclearreasonfordoingsoand,fortunately,thenumberofsuchreasonsissmall.Pruninginvolvesthecuttingawayofobergrownandunwantedbranches,andtheinexperiencedgardenercanbeencouragedbythethoughtthatmoredamageresultsfromdoingitunnecessarilythanfromleavingthetreetogrowinitsownway.
First,pruningmaybedonetomakesurethattreeshaveadesiredshapeorsize.Theobjectmaybetogetatreeoftherightheight,andatthesametimetohelpthegrowthofsmallsidebrancheswhichwillthickenitsappearanceorgiveitaspecialshape.Secondly,pruningmaybedonetomakethetreehealthier.Youmaycutdiseaedordeadwood,orbranchesthatarerubbingagainsteachotherandthuscausewounds.Thehealthofatreemaybeencouragedbyremovingbranchesthatareblockingupthecentreandsopreventingthefreemovementofair.
Oneresultofpruningisthatanopenwoundisleftonthetreeandthisprovidesaneasyentryfordisease,butitisawoundthatwillheal.Oftenthereisaracebetweenthehealingandthedeseaseastowhetherthetreewillliveordie,sothatthereisaperiodwhenthetreeisatrisk.Itshouldbetheaimofeverygardenertoreducewhichhasbeenprunedsmoothandclean,forhealingwillbesloweddownbyroughness.Youshouldallowthecutsurfacetodryforafewhursandthenpaintitwithoneofthesubstancesavailablefromgardenshopsproducedespeciallyforthispurpose.Pruningisusuallywithoutinterferencefromtheleavesandalsoitisveryunlikelythatthecutsyumakewillbleed.Ifthisdoeshappen,itis,ofcourse,impossibletopaintthemproperly.
1.Pruningshouldbedoneto______.
b.improvetheshapeofthetree
c.getridofthesmallbranches
d.makethesmallbranchesthicker
2.Treesbecomeunhealthyifthegardener______.
a.allowstoomanybranchestogrowinthemiddle
b.doesnotprotectthemfromwind
c.forcesthemtogrowtooquickly
d.damagessomeofthesmallsidebranches
3.Whyisaspecialsubstancepaintedonthetree?
b.Topreventdiseaseenteringawound
4.Agoodgardenerprunesatree______.
a.atintervalsthroughouttheyear
c.occasionallywhennecessary
5.Whatwastheauthor'spurposewhenwritingthispassage?
a.Togivepraticalinstructionforpruningatree.
b.Togiveageneraldescriptionofpruning
c.Toexplainhowtreesdevelopdiseases
d.Todiscussdifferentmethodsofpruning.
答案：babca
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