The man became a famous writer when he was .A. in his fiftyB. in his fiftiesC. in fifty y

问题补充：

The man became a famous writer when he was .

A. in his fifty

B. in his fifties

C. in fifty years old

D. in fifties

答案：

A. in his fifty

(答案→)B. in his fifties

C. in fifty years old

D. in fifties

解析：在某人几十岁的时候，英语中用in one’s +数词的复数形式，句意：这个人当他是50几岁时就变成了一个著名的作家。故选B.