compound surd

例句：

1. 1. The scientist found a surd in the ocean.
   科学家在海里发现了一个苏尔德。
2. 2. The sphere of influence is expanding rapidly.
   影响范围正在迅速扩大。
3. 3. The shell of the turtle is a protective covering.
   乌龟的壳是一种保护性的覆盖物。