◎ 题干
—When _____ he first sing a song?
—When he was three years old.
[     ]
A. did            
B. does            
C. is      
D. was
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“—When _____ he first sing a song?—When he was three years old.[ ]A. did B. does C. isD. was…”主要考查了你对  【助动词】【一般过去时】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。