(1), the majors corresponding to Grade One are: science and engineering, and Grade One includes mathematics, linear algebra and probability statistics.
(2) The majors corresponding to the second year of junior college are: economics, agronomy, medicine, management, and the second year has the highest proportion of advanced mathematics.
(3) The corresponding majors in the third year of higher education are: philosophy, law, education, literature, history and art.
Difficulties: How to determine the point M? Because the side lengths of the left right-angled triangle are 3,