Name the coach for may 20, 2010
CREATE TABLE "table1_2140071_10" (
  "season" real,
  "episode" real,
  "episode_summary" text,
  "premier_date" text,
  "external_link" text,
  "coach" text
);
SELECT "coach" FROM "table1_2140071_10" WHERE "premier_date"='May 20, 2010';