挡土墙后的填土为Ⅱ类土时,就是碎石土,且密实为中密。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
挡土墙后的填土为Ⅱ类土时,就是碎石土,且密实为中密。
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