The rolling operation of a single contract is to buy low and sell high, and open low and go high. This is a liquidation in the opposite direction, but it is actually a single order, not a general hedging. The real hedging should be two-way single, that is, multiple single directions and empty single directions, that is, two completely opposite positions. To roll, a part of the bottom position must be reserved, and the bottom position must also be reserved for two-way single hedging, otherwise the rolling operation is difficult.

Multi-order operation is low position opening and high position closing, and empty order operation is high position opening and low position closing. This method is more suitable for the shock stage of the box. If the rhythm is well grasped, the short-term income is good, but the box cannot last indefinitely. Once the box is effectively broken, the trend will enter a new unilateral trend, and then the positions in one direction must be closed, either more than one order or empty.