axi-symmetric shell

例句：

1. 1. The two sides of the coin are not symmetrical.
   硬币的两面不对称。
2. 2.The design is symmetrical, which makes it look more balanced and elegant.
   设计对称，看起来更平衡和优雅。
3. 3.The symmetry of the pattern is what attracts people to it.
   图案的对称性吸引了人们。