填空题
A. by social and economic changes
B. guided self-study and correspondence courses
C. by studying together with children
D. what they did not manage to learn earlier
E. dates back to the eighteenth century
F. mass production
填空题 Some adults want to learn ______.
填空题 There are various forms of adult education, including ______.
填空题 Adult education has been made necessary by ______.
填空题 The earliest organized adult education originated in ______.