圈梁必须是封闭的,当砌体房屋的圈梁被门窗洞口截断时,应在洞口上部增设相同截面的附加圈梁,附加圈梁与原圈梁的搭接长度不应小于其垂直距离的多少倍(且不得小于1m)?()
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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