First of all, it must be clear that doing 660 is to better understand the knowledge, not to brush the questions for the sake of brushing the questions. You should do the questions purposefully, take the postgraduate entrance examination regularly for yourself, grasp the weak places and do more questions, and cultivate the feeling of mathematical thinking and doing questions.

Although 660 chooses to fill in the blanks, it is still difficult. It's hard to master it completely after it's done. In the final stage of review, you can brush the previous wrong questions again. Don't be discouraged when you make many mistakes. This is a good opportunity to check loopholes and fill gaps. Correctness can cultivate some self-confidence, but we must not be complacent. You can do some big problems or difficult problems to improve yourself.