gōng / chǎng / fā / shēng / xiè / lòu / shí / gōng / rén / bì / xū / lì / kè / dài / shàng / fáng / dú / miàn / zhào工厂发生泄漏时,工人必须立刻戴上防毒面罩。When a leak occurs at the factory, workers must put on gas masks immediately.