After many years of hard work Mary and her husband had at last paid all the money they had

问题补充：

After many years of hard work,Mary and her husband had at last paid all the money they had borrowed.

A. for

B. out

C. in

D. off

答案：

A. for

B. out

C. in

(答案→)D. off

解析：pay off偿清；偿还；pay for 为……付款。