6、5BOD的测试标准化rbornediseases水传染的疾病epilimnion表层水hypolimnion深水层thermocline热变形层becomedepletedofoxygen缺氧二、重点句子翻译UNIT21.Environment is the physical and biotic habitat which surrounds us;that which we can see,hear,touch,smell,and taste. 环境是围绕在我们周围物质生命的栖息地,在那里我们可以
7、看到,听到,触到,闻到和品尝到。 2.System,according toWebsterdictionaryis defined as “a set or arrangement of things so related or connected as to form a unit or organic whole;as,a solar system,irrigation system,supply system,the world or universe” 系统,依据韦伯斯特的字典,被定义为“一组
8、或一系列能形成一个整体或者有机整体的相互关联的事物;比如,太阳系统,灌溉系统,供水系统,世界或宇宙” 。 3.Pollution can be defined as an undesirable change in the physical,chemical,or biological characteristics of the air,water,or land that can harmfully affect the health,surviva