Question

(   ) 12. He became a worker when he was        his         .

   A. in,twenty   B. at,twenties   C. at,twenty   D. in,twenties

Answer 1

12. D ine one's twenties/thirties/forties等表示"在某人二十几岁、三十几岁、四十几岁的时候"，不指具体的某一岁。