shell-to-shell distance

例句：

1. 1.The researchers found that the shell-to-shell distance between the two species was significantly different.
   研究人员发现两种物种之间的壳到壳距离显著不同。
2. 2. The scientists used a technique called shell-to-shell separation to study the behavior of marine animals.
   科学家们使用一种叫做壳到壳分离的技术来研究海洋动物的行为。
3. 3.The distance between the two countries is measured in kilometers, which is much greater than the shell-to-shell distance between them.
   两国之间的距离以公里计，这远大于它们之间的壳到壳距离。