, he went to Australia to study English.A. When a boy of 12B. He was 12 years oldC. When h

, he went to Australia to study English.
A. When a boy of 12
B. He was 12 years old
C. When he was the age of 12
D. When was 12

(答案→)A. When a boy of 12B. He was 12 years oldC. When he was the age of 12D. When was 12解析：考查省略。当主句和从句的主语一致，而从句又是主语+be动词的形式，这时从句的主语和be动词可以省略。故When a boy of 12 = When he was a boy of 12，故选A。

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