You can only make two mistakes in multiple-choice questions, but you can't make mistakes in big questions. The full score of mathematics in the college entrance examination is 150, but the score of a big question in the test paper is 10, and the score of a multiple-choice question is 5. Therefore, if you want to test 140, candidates can only write two multiple-choice questions wrongly in the whole test paper, and no big questions can be wrong, which requires students to have solid knowledge and good problem-solving ideas.