—Mark broke his leg when he was playing football . —was that ?A. Since when B. Since when

问题补充：

—Mark broke his leg when he was playing football .

—was that ?

A. Since when

B. Since when ago

C. How long

D. How long ago

答案：

A. Since when

B. Since when ago

C. How long

(答案→)D. How long ago

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