Question: Which unique cities are in Asian countries where Chinese is the official 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  =  't' and t2.language  =  'chinese' and t1.continent  =  "asia"