沉井基础适用于上部荷载较大,结构对基础的变位敏感,而表层地基土的允许承载力不足,做扩大基础开挖工作量大或支撑困难时在一定深度内有好的持力层,或不便使用桩基时。( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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