In this lesson, regarding current practical problems, I'll discuss several points about line treatment and tool requirements: **Figure 1:** The tool for refining cloud-shoulder lines must not be used together with the large rib tool. Only one tool at a time. You must use separate tools for refining lines and for the large rib work. Cloud-shoulder lines should have the character of cloud-shoulder lines, not just carving out a groove. **Figure 2:** The corner below the lid line should not be refined all together with the flange. **Figure 3:** The two lines where the lid meets the body must be smooth and rounded, and where the two lines intersect they must fit together properly. Figure 3 does not meet requirements—it's not rounded. What's the reason? Mainly it's still a tool problem. Nowadays some people refine the lid flange and lid together, which cannot produce the desired effect, and the lid edge will not be smooth and rounded. **Figure 4:** For the lid-body junction of a square lid plate, the diagram on the left is incorrect—it's not straight. It should be as shown in the diagram on the right. **Figure 5:** The corners at the lid junction must be handled well, achieving both aesthetic appeal and resistance to damage.