Elective science should start from the second year of high school. General senior high school students learn five books in Grade Two, that is, compulsory 1 compulsory 2, compulsory 3 and compulsory 5 in science. In the last year of Grade Three, they also learn elective 2- 1 2-2 2 2-3 and two books. These two books are different in different provinces. I know that elective 4-2 and elective 4-4 of Jiangsu University are matrix and parameter equation respectively.