Table: port_leg_election_1991_2
Columns: date_released
polling_institute
social_democratic
socialist
green_communist
democratic_and_social_centre
lead

Question: What's the date released when there was 9.7% of Green communist?
SQL: SELECT "date_released" FROM port_leg_election_1991_2 WHERE "green_communist" = '9.7%'

Question: What's the green communist when Euroteste/JN is the polling Institute?
SQL: SELECT "green_communist" FROM port_leg_election_1991_2 WHERE "polling_institute" = 'euroteste/jn'