Gōng / chǎng / bì / xū / yán / gé / chǔ / lǐ / fèi / qì / bì / miǎn / dài / ào / xīn / wū / rǎn / zhōu / wéi / huán / jìng工厂必须严格处理废气,避免戴奥辛污染周围环境。The factory must properly treat its exhaust to prevent dioxin from polluting the surrounding environment.