The Yangtze River runs east-west, and the boat sails from the south to Cao Cao's water village on the north bank. The bow of the boat faces north, the area to receive arrows is small, and there are few straw people. After turning the bow of the boat to the west and the stern of the boat to the east, The area where arrows are received is larger and there are more straw men, so the speed of "borrowing arrows" must be faster. As time goes by, Cao Cao will be suspicious. If Cao Cao understands, the strategy will not work, and the plan of borrowing arrows will not be realized.