It's in the bag
某事已确定成功或稳操胜券。
用于自信地预测成功或确认结果。
例句
With his lead in the polls, the election is in the bag for him.
典故来源
源自19世纪狩猎或赌博，猎物放入袋中即表示成功，后泛指确定之事。