Jack won the first prize in the computer competition. Two years of hard work and patience

问题补充：

Jack won the first prize in the computer competition. Two years of hard work and patience in the end.

A. paid up

B. paid out

C. paid back

D. paid off

答案：

A. paid up

B. paid out

C. paid back

(答案→)D. paid off

解析： 考查短语辨析。pay up 全部付清；pay out付出（钱）；报复 pay back偿还 pay off还清债务；取得成功；得到好的结果。根据意思，两年的努力工作和耐心最后得到了回报。