This essay introduces the main features of rodenticide:the development,classification,chemical structures,toxicity and so on.

The action mechanism of TiO₂ as a photocatalyst and its applications in environment protection are reviewed briefly in this article.The factorsof affecting photocatalytic efficiency of TiO2and the ways to solve it are also discussed.

Scientific methods are essential in chemical education in middle schools.The definition of scientific methods,their characteristics,types and strutures were discussed in this paper.Strengthening the education of scientific methods plays an important role in promoting student's quality,ensuring their sustainable development and reforming course materials.The author put forward ideas concerning the importance of scientific methods in science education,the approaches we should employ to teach scientific methods and how we can carry out the education of scientific methods effectively.