CREATE TABLE "opinion_polls" (
  "source" text,
  "date" text,
  "de_sus" text,
  "zares" text,
  "nlpd" text
);

Question: What is the percentage for Zares on May 21–22?
SQL: SELECT "zares" FROM "opinion_polls" WHERE "date"='may 21–22';

Question: What is the source for 7% DeSUS?
SQL: SELECT "source" FROM "opinion_polls" WHERE "de_sus"='7%';

Question: What is the source for Zares at 8.6%?
SQL: SELECT "source" FROM "opinion_polls" WHERE "zares"='8.6%';

Question: What is the source corresponding to a date of May 25–27?
SQL: SELECT "source" FROM "opinion_polls" WHERE "date"='may 25–27';