The supply trend line and the demand trend line are used to judge the main trend trend, and the supply and demand trend line is used to judge the local supply and demand intensity. When the supply and demand channel is located under the supply and demand trend channel, it is a strong downward trend; when the supply and demand channel is located above the supply and demand trend channel, it is a strong upward trend.In an uptrend, when the candle chart shows a significant uprush and the closing price has not been able to break through the supply line since then, we think the uptrend will present a red flag.In a downtrend, when the candle chart has a significant downtrend rebound and the closing price has not been able to break the demand line since then, we believe that the downtrend will be reversed.