Which seasons were directed by Nelson McCormick?
CREATE TABLE "table1_17355933_1" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text
);
SELECT "title" FROM "table1_17355933_1" WHERE "directed_by"='Nelson McCormick';