hi, what is the maximum low temperature at Amersham station?
SELECT max ( t1.low_temperature )  FROM weekly_weather AS t1 JOIN station AS t2 ON t1.station_id   =   t2.id WHERE t2.network_name   =   "Amersham"
maximum low temperature refers to MAX(low_temperature); at Amersham station refers to WHERE station.network_name = 'Amersham';