指数博彩，差额投注（判断得分、点数等预测数目过高还是过低的体育博彩，输赢款额依判断的准确程度而定）a type of betting on a sports event in which you bet money on whether you think the predicted number of goals, points, etc. is too high or too low. The amount of money you win or lose depends on the extent to which you are right or wrong.
