His hard work paid when he got the result.A. backB. overC. offD. for

问题补充：

His hard work paid when he got the result.

A. back

B. over

C. off

D. for

答案：

A. back

B. over

C. off

D. for

解析：考察固定词组。Pay off指努力得到回报。结合句意可知C正确。句意：他当得知结果的时候，他的努力工作得到了回报。