I don't understand the second question. People who buy things have to pay. If the goods are sold, the exchange will deduct 80% of the payment from the location of the corresponding buyer's customer company and pay it to the seller upon delivery. The remaining 20% will be transferred after the buyer confirms that there is no problem with the VAT invoice issued by the seller, and then the seller receives the full amount.
If both parties close their positions before the last trading day, then physical delivery is not involved. However, the standard warehouse receipt of a certain number of physical objects registered by the seller is valid. For example, the standard warehouse receipt for wheat is valid for 2 years. That is, warehouse receipts registered in 2007 must be cancelled on the last trading day of July 2009. If there is delivery, the buyer can cancel the warehouse receipt after buying it, and go to the delivery warehouse to get the spot after handling the delivery notice. If there is still no match, that is to say, what should I do if I finally close all my positions? Then the seller can only cancel his warehouse receipt, pick up the goods and try to digest it in the spot market. In addition, the circulation of the underlying spot futures warehouse receipt is not only one of the delivery methods, but also the spot conversion and warehouse receipt transaction, which can be handled at any time and is more flexible than delivery.
Generally speaking, if all positions are finally closed, the seller can change hands in cash at a later time, but if the warehouse receipt expires and has not been sold, the physical spot can only be taken away by the seller himself.