David’s effort was because he won the first prize in the English speech contest which m

问题补充：

David’s effort was , because he won the first prize in the English speech contest, which made his classmates surprised.

A. paid off

B. paid back

C. paid for

D. paid up

答案：

(答案→)A. paid off

B. paid back

C. paid for

D. paid up

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