Obama had trouble winning working class support in his primary battles with former rival Hillary Clinton, but pollster Clay Richards says he appears to be making some inroads.
The roof of the Primary School was pulled away from the learning space of the interior though, and a perforated clay ceiling with ample ventilation was introduced.
小学的屋顶远离内部的学习空间,通过多孔粘土天花板来为屋顶提供足够的通风。
3
Stone and clay were the primary masonry materials in the Middle Ages and later.