沟槽开挖断面应符合施工组织设计要求,机械开挖时槽底预留20~30cm由人工挖至设计高程,整平。万一出现局部超挖,可用挖槽原土回填夯实。 ( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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