Database: train_station
Question: Find the names of the trains that do not pass any station located in London.
SQL: select t2.name from train_station as t1 join train as t2 on t1.train_id  =  t2.train_id where t1.station_id not in (select t4.station_id from train_station as t3 join station as t4 on t3.station_id  =  t4.station_id where t4.location  =  "london")