I think you should be a freshman. In fact, college and high school are two completely different modes of life and study. University study does not rely on a large number of repetitive questions to improve their ability and level. Like advanced mathematics, it is usually enough to understand the ideas and solving methods of such problems, and the rest is only the calculation process. That's not the most important thing. Finding ideas is the most important thing. You don't need to do many questions, just look and think. Freshmen majoring in mechanical engineering must learn descriptive geometry and mechanical drawing. Descriptive geometry is the foundation, cultivate your spatial imagination and judgment, and understand the projection relationship; Mechanical drawing is based on descriptive geometry, and the actual objects are projected on the view through certain rules (including occlusion relationship, etc.). You need to think more about these things. You can usually observe and practice with what you have in your hand. Don't use the tactics of asking questions in high school. It's useless.