The importance of the seismic design of the primary-secondary systems is introduced and the dynamic characteristics of the combined systems are outlined in the paper.
2
陨坑中心可能是由于不同寻常的下层地质结构导致的,也有可能因为幸运的二次撞击而形成的。
The central crater could be formed by unusual layers below the surface, or from a lucky second impact.
3
第二次遍历使用与前一个例子十分类似的分组逻辑创建了一个两层结构:chapter和section。
The second pass USES grouping logic much like the previous example to create two levels of structure: chapter and section.