我认为在讲解物质的制法时,必须注意讲清楚以下各点,才能使学生真正掌握那种物质的制法。(一)了解物质的成分、性质及该物质与其它物质间的关系(1)单质的制取。要使学生自觉地、积极地了解某单质的制法,就必须使学生知道组成该单质的元素在自然界中存在的情况及该单质的性质。如在讲解氧气的制法时,可先使学生回忆氧在自然界中的存在情 In my opinion, when explaining the material system, we must pay attention to making clear the following points in order to enable students to truly grasp the material system. (A) understand the composition of the substance, nature and the substance and other substances (1) the preparation of simple substance. In order for students to consciously and actively understand the method of making a particular element, students must be made aware of the fact that elements that make up the element exist in nature and the nature of the element. As explained in the oxygen system of law, students can first remember the existence of oxygen in nature