Table: tianwan_nuclear_units
Columns: unit
reactor_type
net_capacity
gross_capacity
construction_started
electricity_grid
commercial_operation
shutdown

Question: What reactor type that has a commercial operation of —, and a tianwan-7 unit?
SQL: SELECT "reactor_type" FROM tianwan_nuclear_units WHERE "commercial_operation" = '—' AND "unit" = 'tianwan-7'

Question: What was the net capacity with a gross capacity of 1,126 mw, and a Unit of tianwan-4?
SQL: SELECT "net_capacity" FROM tianwan_nuclear_units WHERE "gross_capacity" = '1,126 mw' AND "unit" = 'tianwan-4'

Question: What commercial operation that has a gross capacity of 1,126 mw, and a unit of tianwan-4?
SQL: SELECT "commercial_operation" FROM tianwan_nuclear_units WHERE "gross_capacity" = '1,126 mw' AND "unit" = 'tianwan-4'