CREATE TABLE table_67942 ("Country" TEXT, "Player name" TEXT, "Period" TEXT, "Position" TEXT, "Matches" TEXT, "Goals" TEXT)

Name the period with matches of 0 0 of portugal
SELECT "Period" FROM table_67942 WHERE "Matches" = '0 0' AND "Country" = 'portugal'
SELECT "Period" FROM "table_67942" WHERE "Country" = 'portugal' AND "Matches" = '0 0'