购买等级 meaning in English

buyclasses

The amount a price would be reduced to purchase a commodity of lesser grade ； ( 2 ) sometimes used to refer to the price differences between futures of different delivery months ， as in the phrase “ july at a discount to may ” ， indicating that the price for the july futures is lower than that of may
由于购买等级较低的商品而产生的支出被减少的部份； ( 2 )也指不同月份的期货合约间的价差，如“ 7月合约对5月合约贴水”就是指7月合约的价格比5月合约的价格要低。