The roof slice longwall method increases the work of laying false roof for next slice.
长壁采煤法的采煤工艺具有多重特点：顶分层采煤增加了要为下分层填设假顶的工作。
The man-made false roof quality is very important to the mine pit safety in production.
人工假顶的质量对矿井的安全生产至关重要。
The man-made false roof quality is very important to the mine pit safety in production.
人工假顶的质量对矿井的安全生产至关重要。
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