roof layer是什么意思

用法例句

Based on full and accurate field materials, the distribution characteristic of methane in shallow stratum of Shanghai is analyzed in this paper.

针对上海地下工程中遇到的浅层沼气地质灾害问题,本文搜集分析了大量的实测资料,总结了上海地区浅层沼气的产出和分布规律,并最终尝试从地质灾害的角度对其进行分区。