We studied 4-5 at that time, and then the teacher told us 4-4 after reviewing it all, because he said, "Two cities are optional, and one is not mandatory?" It means something like this. However, other classes in our grade have not studied (of course, it may be because we are key classes), so it is difficult to say that there is a fixed standard, mainly according to our own learning situation. If you think learning one subject is enough, you won't lose points in multiple-choice questions. One is enough. If you feel really unsure, you can learn both, and the teacher can teach himself without talking. After all, these two elective courses are not difficult and have little content.