shell edge

例句：

1. 1. The shell edge is smooth and shiny.
   壳边缘光滑且有光泽。
2. 2. The shell edge is where the shell meets the body of the animal.
   壳边缘是壳与动物身体接触的地方。
3. 3.The shell edge is where the shell attaches to the body of the animal.
   壳边缘是壳附着到动物身体的地方。