Question

The house is finished at last. All their hard work has _____

Answer 1

C

这题考查词组辨析：paid back报答，偿还，paid up全部还清，付清

paid off （努力）有回报，成功， paid for为…付钱，根据句意：这个房子最后完成了，所有的努力都没白费。选C。