问题补充:
My head-teacher helped me a lot when I was in trouble. I do wish I could do something for him one day.
A. in turn
B. in common
C. in return
D. in theory
答案:
A. in turn
B. in common
(答案→)C. in return
D. in theory
解析:选项A“依次,轮流”; 选项B“共有”; 选项C“作为报答”; 选项D“在理论上”;句意:我的班主任在我困难时帮了我很多,我多么希望我有一天能够为他做件事作为报答。