CREATE TABLE table_name_25 (reactor_type VARCHAR, commercial_operation VARCHAR, unit VARCHAR)

What reactor type that has a commercial operation of , and a tianwan-7 unit?
SELECT reactor_type FROM table_name_25 WHERE commercial_operation = "—" AND unit = "tianwan-7"
SELECT "reactor_type" FROM "table_name_25" WHERE "commercial_operation" = "—" AND "tianwan-7" = "unit"