Pinduoduo, what do you mean by spelling one more for free?

In Pinduoduo, you can get free of charge when you spell another order, that is to say, after you buy a certain amount of goods on the designated page, you can randomly draw free of charge, but the free of charge is automatically drawn by the system, and most of them are not returned to the personal payment account in cash, but distributed to the personal center in the form of non-threshold coupons, and most of the coupons are 3 to 7 days, and they are valid within 3 to 7 days, which can increase the purchase amount of users in Pinduoduo.