2。 The maximum loss due is 5 yuan/unit, which is the difference between the two agreed prices.

3。 In any case, there will be no profit due, and the best case is S&; P is above 505, so it's all waste paper.

4。 Considering the first two profits, regardless of the time value of funds, the breakeven point is 503.

Below 503, you will lose money, and above 503, you will make a profit.