元素和化合物的知识的是贯穿九年级化学的一条主线。在平时学习时由于时间紧、任务重,同学们普遍存在着记不熟或把不同物质的化学性质记混淆,练习时不能正确运用这些知识的现象。复习的重要任务就是理清各物质性质、制法之间的关系,使所学知识得到一次升华。但在复习中让同学们重复记忆这些知识会感觉到枯燥无味 Knowledge of elements and compounds is one of the main lines of chemistry throughout the ninth grade. Due to the lack of time and heavy tasks during normal schoolwork, students generally do not understand or confuse the chemical properties of different substances, and can not correctly use the knowledge when practicing. The important task of reviewing is to sort out the relationship between the nature of the material and the system of law so that the knowledge learned will be sublimated once. However, in the review so that students repeat the memory of these knowledge will feel boring