CREATE TABLE table_20511 ("Line" CLOB, "Terminals" CLOB, "Status" CLOB, "Length" CLOB, "Total number of stations" FLOAT, "Operator" CLOB)

Which operator runs the Mamariga shuttle line?
SELECT "Operator" FROM table_20511 WHERE "Line" = 'Mamariga Shuttle'
SELECT "Operator" FROM "table_20511" WHERE "Line" = 'Mamariga Shuttle'