半通行地沟
半通行地沟 指人能半蹲半站在里面进行安装和检修的管沟,其净空高度一般小于1.6m,适用于管路较短,数量不多,不经常检修的情况,安装和检修时可打开活盖板。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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