Only when 30 years old to learn English.
A. was he; did he begin
B. he was; he began
C. he was; did he begin
D. was he; he began
网友回答
A. was he; did he begin
B. he was; he began
(答案→)C. he was; did he begin
D. was he; he began
解析：考查部分倒装。Only+时间状语从句，放在句首时，后面主句要部分倒装，而从句不倒装。所以选C。