chéng shì / de / dì gōu / xū yào / dìng qī / qīng lǐ / fǒu zé / huì / dǔ sè / pái shuǐ / xì tǒng城市的地沟需要定期清理,否则会堵塞排水系统。City ditches need regular cleaning, otherwise they will block the drainage system.