what's the alloy with series being ii series
CREATE TABLE "1_yuan" (
  "year" real,
  "denomination" text,
  "alloy" text,
  "reverse" text,
  "diameter" text,
  "weight" text,
  "obverse" text,
  "mintage" real,
  "series" text
);
SELECT "alloy" FROM "1_yuan" WHERE "series"='II series';