huí / cǎi / guò / chéng / zhōng / bì / xū / jiā / qiáng / tōng / fēng / bìng / jí / shí / jiǎn / chá / xiàng / dào / ān / quán

回采过程中必须加强通风，并及时检查巷道安全。

Ventilation must be improved during ore extraction, and the safety of the tunnels must be checked promptly.