1. For a 30-day account period, the price can be raised appropriately, because customers can pay for the goods in a relatively short time, so they may be more inclined to buy products with higher price but better quality.

2. For a 60-day account period, the price level can remain stable, because customers need to wait longer to pay for the goods, so they may need better prices to attract them to buy.

3. Under the 90-day accounting period, the time value of payment needs to be considered. In this case, the price may need to be considered, because customers need to wait longer to pay for the goods, and there is a certain risk of default.