primary structural elements

例句：

1. 1. The primary structuralelements of a building are the walls and the roof.
   建筑物的初级结构元素是墙壁和屋顶。
2. 2. In the study of language acquisition, primary structural elements play a crucial role in understanding how children learn to speak.
   在语言习得研究中，初级结构元素在理解儿童如何学习说话方面起着至关重要的作用。
3. 3. The primary structural elements of the new design are more efficient and aesthetically pleasing.
   新设计的初级结构元素更加高效且美观。