1. It is probably better to choose polar coordinates as an elective course in the college entrance examination. Polar coordinates are relatively fixed and easy to do. It is more convenient to write down the fixed formula and replace it during the exam.

2. The first elective course is mainly about learning series, the second elective course is about learning derivatives, and the third elective course is about learning conic. In contrast, it is relatively simple to take the first compulsory book.