Question: what is the average b score when the gymnast is Kōhei Uchimura ( JPN )?
SQL: SELECT AVG("B Score") FROM "2-18662017-2" WHERE "Gymnast" = 'Kōhei Uchimura ( JPN )';

Question: what is the b score when the a score is 6.9?
SQL: SELECT "B Score" FROM "2-18662017-2" WHERE "A Score" = 6.9;

Question: what is the sum of the b score when the a score is 6.6 and the total is 15.6?
SQL: SELECT SUM("B Score") FROM "2-18662017-2" WHERE "A Score" = 6.6 AND "Total" = 15.6;