You have $365438 +0.2 in your hand, and you bought a barrel of ICBC crude oil. Assume that the transaction price remains unchanged (or fluctuates, but at the end of this transaction, the price just changes back to the original purchase price of 3 1.2 and the selling price of 3 1.0). Because of the price difference (equivalent to the handling fee), the final selling price is $365,438 +0.0, with a loss of 0.2.

Suppose you don't close your position before the end of this period, and move to another period, with the buying price of 3 1.6 and the selling price of 3 1.4.

When you turn over, close your position and then open it. When you turn over, you have $365,438+$0.0 (loss of $0.2), and then open the position again.

At the time of rollover, the hand was $365,438 +0.0, with (3 1.0 divided by 3 1.6) barrels, less than 1 barrel. Assuming that the transaction price is always the same, the final money is (3 1.0 divided by 3 1.6) barrel multiplied by 30.