Shǐ / yòng / hàn / jù / shí / bì / xū / xiān / jiǎn / chá / qì / guǎn / shì / fǒu / lòu / qì使用焊炬时,必须先检查气管是否漏气。When using a welding torch, you must first check whether the gas hose is leaking.