SELECT "Class to 1928" FROM table_64027 WHERE "Year(s) of Manufacture" = '1921/23' AND "Class from 1928" = 'bci-21'
Which class to 1928 value had years of manufacture of 1921/23 and class from 1928 of BCi-21?
CREATE TABLE table_64027 (
    "Class to 1928" text,
    "Class from 1928" text,
    "Seats" text,
    "Quantity" real,
    "Year(s) of Manufacture" text,
    "Remarks" text
)