“What did you use to do in your free time as a child?” Mary asked me.

A. Mary asked me what I used to do in my free time as a child.

B. Mary asked me what I used to do on my free time as a child.

C. Mary asked me what did I use to do in my free time as a child.

D. Mary asked me what I used to do in my free time when a child.

E9- TĐ- Unit 4 (1)