CREATE TABLE "table1_1566852_6" (
  "date" text,
  "cover_model" text,
  "centerfold_model" text,
  "interview_subject" text,
  "20_questions" text,
  "pictorials" text
);

Question: How many times was Jillian Grace the centerfold model?
SQL: SELECT COUNT("date") FROM "table1_1566852_6" WHERE "centerfold_model"='Jillian Grace';

Question: What were the interview subjects on those occasions where Bai Ling was the cover model?
SQL: SELECT "interview_subject" FROM "table1_1566852_6" WHERE "cover_model"='Bai Ling';

Question: How many total interview subjects wererthere when the centerfold model was Tamara Witmer?
SQL: SELECT COUNT("interview_subject") FROM "table1_1566852_6" WHERE "centerfold_model"='Tamara Witmer';

Question: What's the subject of 20 questions in those issues where Jillian Grace is the centerfold model?
SQL: SELECT "20_questions" FROM "table1_1566852_6" WHERE "centerfold_model"='Jillian Grace';

Question: Who were the cover model(s) on the 4-05 issue?
SQL: SELECT "cover_model" FROM "table1_1566852_6" WHERE "date"='4-05';

Question: Who was on the cover when the 20 questions subject was Scarlett Johansson?
SQL: SELECT "cover_model" FROM "table1_1566852_6" WHERE "20_questions"='Scarlett Johansson';