Question

--- Believe me, all your efforts will _______ some day.

Answer 1

C

词义辨析。pay back偿还，报复；pay down即时支付，付定金；pay off 付清，取得成功；pay for为……付款。句意：相信我，你的所有努力有一天一定会获得成功。谢谢你的鼓励。所以选C。