In order to the debt the couple has worked hard for years with little food and only a sm

问题补充：

In order to the debt, the couple has worked hard for years with little food and only a small room to live in and never a moments rest.

A. pay for

B. pay back

C. pay

D. return back

答案：

A. pay for

(答案→)B. pay back

C. pay

D. return back

解析：pay back表“偿还”，pay for仅表“付钱”。