工作面沿倾斜和仰斜方向及开切眼一切煤体上形成支撑压力,其在工作面采过一段时间后,不再发生明显变化,称为固定支撑压力或残余支撑压力。()
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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