Question: What is the average quantity for coaches manufactured in 1921/23, and had 40 seats?
SQL: SELECT AVG("Quantity") FROM "2-18734371-2" WHERE "Year(s) of Manufacture" = '1921/23' AND "Seats" = '40';

Question: Which class to 1928 value had years of manufacture of 1921/23 and class from 1928 of BCi-21?
SQL: SELECT "Class to 1928" FROM "2-18734371-2" WHERE "Year(s) of Manufacture" = '1921/23' AND "Class from 1928" = 'BCi-21';

Question: What is the smallest quantity having a Class to 1928 of BDi-21?
SQL: SELECT MIN("Quantity") FROM "2-18734371-2" WHERE "Class to 1928" = 'BDi-21';

Question: Which class from 1928 had a class to 1928 of BDi-21?
SQL: SELECT "Class from 1928" FROM "2-18734371-2" WHERE "Class to 1928" = 'BDi-21';

Question: What were the remarks for the coach having a class from 1928 of Cid-21b?
SQL: SELECT "Remarks" FROM "2-18734371-2" WHERE "Class from 1928" = 'Cid-21b';