The contract price has fallen below the middle line of the Bollinger Bands, reaching a low of 136420 points, marking the first dip.
The criterion for judging the second dip is that the low point of the second dip must be higher than the low point of the first dip. When it is observed that the price's second dip (at the circled point) cannot break through the low point of the first dip and is unable to fall below the lower line of the Bollinger Bands, as long as the price rises above the middle line of the Bollinger Bands again, we can use this as a basis to enter a long position.