Design a pneumatic circuit that can realize "fast forward-slow forward-fast backward" of the cylinder, and explain the working principle. Urgent urgent answer accurate evaluation first.

As shown in the schematic diagram, when the cylinder is extended, the three-way solenoid valve C is in the closed position, and the cylinder is exhausted by the muffler E with the speed regulating valve and fast-forwarded. When the three-way valve is switched electrically, the cylinder is exhausted by the speed regulating valve D instead, which makes it move slowly; When the cylinder retracts, the cylinder exhausts quickly through quick exhaust valve F. It should be noted that according to this connection, when the cylinder retracts, the three-way solenoid valve C must be in the energized state. When the cylinder is at a low speed, it should be noted that if the required speed is lower than 50mm/s, the cylinder should use a low-friction cylinder, otherwise crawling will occur.