某构件采用机械张拉后张法施工,孔道长度为29.8m,预应力筋为单根粗钢筋,每根长88米,两端均用螺丝端杆锚具,则对焊接头数量为()个。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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