问答题宇宙在物理意义上被定义为所有的空间和时间 统称为时空 及其内涵 元宇宙是一个新的时空概念 其新意在于对于宇宙的唯一性的质疑和挑战
问答题Wking class families in the United States are usually nuclear many studies indicate that wking class couples marry f love f money Upper class couples may marry f love but their c
