The order of classes in different regions is different, but if it is a three-volume region in China, compulsory 5 will be studied in the second half of senior two. In areas where the national college entrance examination has three volumes, the teaching order of senior high school mathematics is basically compulsory one and four in the first half of senior high school, compulsory five and three in the second half of senior high school, and compulsory two and elective courses in the first half of senior high school. Take science as an example, the elective courses are 2- 1, 2-2, 2-3, 4-4 and 4-5 in turn, and the new courses will basically end in the second half of senior two, probably the last one.