平桥结构有梁式或板式平桥。
钢筋混凝土楼梯按结构受力状态可分为梁式、板式、折板悬挑式和螺旋式,前两种属于空间受力体系;后两种属于平面受力体系。( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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