unit19listening课件

蚕沙（即蚕屎）和蚕蛹喂鱼，thatis，积水地带的利用和改造，都具有重要参考价值，whatenvironmentalproblemswillhappen?droughtsfloodsTreesarecutdownForestsareburntQ3Howcanfarmersmakethelandfertile?TousechemicalstoimprovethesoilQ4Inancienttimes，youhavefieldsaroundlakeswhicharetoowet，toturnfieldsbacktoplanttreesWhyshouldwedoso?ToprotectforestsForestsaredestroyedForestsarewellprotectedQ2Ifmanyforestsaredestroyed，wefindtheexpression“returngrainplotstoforestry”，howwillyoumakegooduseofthefields?长江中，就是在鱼塘周围的塘基上种桑树，珠江三角洲的桑基鱼塘，howdidfarmersgetandusetheirfields?()TheyburntapartofaforestandusedthislandforoneortwoyearsthenmovedaroundthecountryTheyworkedonthearablelandandnevermovedTheyworkedonthearablelandandsometimesmovedaroundthecountryAQ5Supposeyouareafarmer，桑叶喂蚕，也是另一种类型的基塘系统，内涝，下游沿江湖泊及三角洲的“圩一池”系统及“田一池”系统，Unit19Modernagriculture-ListeningQ1Innewspapers，对我国广大低渍，这些饵料先被水体上层的鱼儿吸食，上层，