Database: world_1
Question: Which unique cities are in Asian countries where Chinese is the unofficial language ?
SQL: select distinct t3.name from country as t1 join countrylanguage as t2 on t1.code  =  t2.countrycode join city as t3 on t1.code  =  t3.countrycode where t2.isofficial  =  "f" and t2.language  =  "chinese" and t1.continent  =  "asia"